diff --git a/ci/test/00_setup_env_mac.sh b/ci/test/00_setup_env_mac.sh
index 1651c5ec26..9e71da7b82 100755
--- a/ci/test/00_setup_env_mac.sh
+++ b/ci/test/00_setup_env_mac.sh
@@ -17,7 +17,4 @@ export XCODE_BUILD_ID=15A240d
 export RUN_UNIT_TESTS=false
 export RUN_FUNCTIONAL_TESTS=false
 export GOAL="deploy"
-
-# False-positive warning is fixed with clang 17, remove this when that version
-# can be used.
-export BITCOIN_CONFIG="--with-gui --enable-reduce-exports LDFLAGS=-Wno-error=unused-command-line-argument"
+export BITCOIN_CONFIG="--with-gui --enable-reduce-exports"
diff --git a/contrib/devtools/symbol-check.py b/contrib/devtools/symbol-check.py
index ff1678116d..b3e73bb2b9 100755
--- a/contrib/devtools/symbol-check.py
+++ b/contrib/devtools/symbol-check.py
@@ -32,7 +32,7 @@
 # See https://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html for more info.
 
 MAX_VERSIONS = {
-'GCC':       (4,8,0),
+'GCC':       (4,3,0),
 'GLIBC': {
     lief.ELF.ARCH.x86_64: (2,27),
     lief.ELF.ARCH.ARM:    (2,27),
diff --git a/contrib/guix/libexec/prelude.bash b/contrib/guix/libexec/prelude.bash
index 28ca23098d..6c912ca748 100644
--- a/contrib/guix/libexec/prelude.bash
+++ b/contrib/guix/libexec/prelude.bash
@@ -51,7 +51,7 @@ fi
 time-machine() {
     # shellcheck disable=SC2086
     guix time-machine --url=https://git.savannah.gnu.org/git/guix.git \
-                      --commit=77386bdbfe6b0c649c05ab37f08051d1ab3e5074 \
+                      --commit=d5ca4d4fd713a9f7e17e074a1e37dda99bbb09fc \
                       --cores="$JOBS" \
                       --keep-failed \
                       --fallback \
diff --git a/contrib/guix/manifest.scm b/contrib/guix/manifest.scm
index 9206973953..7335596107 100644
--- a/contrib/guix/manifest.scm
+++ b/contrib/guix/manifest.scm
@@ -525,5 +525,5 @@ inspecting signatures in Mach-O binaries.")
           ((string-contains target "-linux-")
            (list (make-bitcoin-cross-toolchain target)))
           ((string-contains target "darwin")
-           (list clang-toolchain-15 binutils cmake-minimal python-signapple zip))
+           (list clang-toolchain-17 binutils cmake-minimal python-signapple zip))
           (else '())))))
diff --git a/depends/packages/native_libtapi.mk b/depends/packages/native_libtapi.mk
index a855c393c6..fb5ab0b4dc 100644
--- a/depends/packages/native_libtapi.mk
+++ b/depends/packages/native_libtapi.mk
@@ -6,7 +6,7 @@ $(package)_sha256_hash=d4d46c64622f13d6938cecf989046d9561011bb59e8ee835f8f39825d
 $(package)_patches=disable_zlib.patch
 
 ifeq ($(strip $(FORCE_USE_SYSTEM_CLANG)),)
-$(package)_dependencies=native_clang
+$(package)_dependencies=native_llvm
 endif
 
 define $(package)_preprocess_cmds
diff --git a/depends/packages/native_clang.mk b/depends/packages/native_llvm.mk
similarity index 67%
rename from depends/packages/native_clang.mk
rename to depends/packages/native_llvm.mk
index 661b9c2c1c..09994eb012 100644
--- a/depends/packages/native_clang.mk
+++ b/depends/packages/native_llvm.mk
@@ -1,16 +1,17 @@
-package=native_clang
-$(package)_version=15.0.6
+package=native_llvm
+$(package)_version=17.0.6
+$(package)_major_version=$(firstword $(subst ., ,$($(package)_version)))
 $(package)_download_path=https://github.com/llvm/llvm-project/releases/download/llvmorg-$($(package)_version)
 ifneq (,$(findstring aarch64,$(BUILD)))
 $(package)_file_name=clang+llvm-$($(package)_version)-aarch64-linux-gnu.tar.xz
-$(package)_sha256_hash=8ca4d68cf103da8331ca3f35fe23d940c1b78fb7f0d4763c1c059e352f5d1bec
+$(package)_sha256_hash=6dd62762285326f223f40b8e4f2864b5c372de3f7de0731cb7cd55ca5287b75a
 else
-$(package)_file_name=clang+llvm-$($(package)_version)-x86_64-linux-gnu-ubuntu-18.04.tar.xz
-$(package)_sha256_hash=38bc7f5563642e73e69ac5626724e206d6d539fbef653541b34cae0ba9c3f036
+$(package)_file_name=clang+llvm-$($(package)_version)-x86_64-linux-gnu-ubuntu-22.04.tar.xz
+$(package)_sha256_hash=884ee67d647d77e58740c1e645649e29ae9e8a6fe87c1376be0f3a30f3cc9ab3
 endif
 
 define $(package)_stage_cmds
-  mkdir -p $($(package)_staging_prefix_dir)/lib/clang/$($(package)_version)/include && \
+  mkdir -p $($(package)_staging_prefix_dir)/lib/clang/$($(package)_major_version)/include && \
   mkdir -p $($(package)_staging_prefix_dir)/bin && \
   mkdir -p $($(package)_staging_prefix_dir)/include/llvm-c && \
   cp bin/clang $($(package)_staging_prefix_dir)/bin/ && \
@@ -20,5 +21,5 @@ define $(package)_stage_cmds
   cp include/llvm-c/ExternC.h $($(package)_staging_prefix_dir)/include/llvm-c && \
   cp include/llvm-c/lto.h $($(package)_staging_prefix_dir)/include/llvm-c && \
   cp lib/libLTO.so $($(package)_staging_prefix_dir)/lib/ && \
-  cp -r lib/clang/$($(package)_version)/include/* $($(package)_staging_prefix_dir)/lib/clang/$($(package)_version)/include/
+  cp -r lib/clang/$($(package)_major_version)/include/* $($(package)_staging_prefix_dir)/lib/clang/$($(package)_major_version)/include/
 endef
diff --git a/depends/packages/packages.mk b/depends/packages/packages.mk
index dd55c939cb..fb52fd4499 100644
--- a/depends/packages/packages.mk
+++ b/depends/packages/packages.mk
@@ -33,7 +33,7 @@ ifneq ($(build_os),darwin)
 darwin_native_packages += native_cctools native_libtapi
 
 ifeq ($(strip $(FORCE_USE_SYSTEM_CLANG)),)
-darwin_native_packages+= native_clang
+darwin_native_packages+= native_llvm
 endif
 
 endif
diff --git a/depends/packages/qt.mk b/depends/packages/qt.mk
index ecf3334aa5..5608e5f073 100644
--- a/depends/packages/qt.mk
+++ b/depends/packages/qt.mk
@@ -22,8 +22,8 @@ $(package)_patches += fast_fixed_dtoa_no_optimize.patch
 $(package)_patches += guix_cross_lib_path.patch
 $(package)_patches += fix-macos-linker.patch
 $(package)_patches += memory_resource.patch
+$(package)_patches += utc_from_string_no_optimize.patch
 $(package)_patches += windows_lto.patch
-$(package)_patches += fix-minimum-macos.patch
 
 $(package)_qttranslations_file_name=qttranslations-$($(package)_suffix)
 $(package)_qttranslations_sha256_hash=a31785948c640b7c66d9fe2db4993728ca07f64e41c560b3625ad191b276ff20
@@ -240,7 +240,6 @@ endef
 define $(package)_preprocess_cmds
   cp $($(package)_patch_dir)/qt.pro qt.pro && \
   cp $($(package)_patch_dir)/qttools_src.pro qttools/src/src.pro && \
-  patch -p1 -i $($(package)_patch_dir)/fix-minimum-macos.patch && \
   patch -p1 -i $($(package)_patch_dir)/fix-macos-linker.patch && \
   patch -p1 -i $($(package)_patch_dir)/dont_hardcode_pwd.patch && \
   patch -p1 -i $($(package)_patch_dir)/fix_qt_pkgconfig.patch && \
@@ -251,6 +250,7 @@ define $(package)_preprocess_cmds
   patch -p1 -i $($(package)_patch_dir)/memory_resource.patch && \
   patch -p1 -i $($(package)_patch_dir)/rcc_hardcode_timestamp.patch && \
   patch -p1 -i $($(package)_patch_dir)/duplicate_lcqpafonts.patch && \
+  patch -p1 -i $($(package)_patch_dir)/utc_from_string_no_optimize.patch && \
   patch -p1 -i $($(package)_patch_dir)/fast_fixed_dtoa_no_optimize.patch && \
   patch -p1 -i $($(package)_patch_dir)/guix_cross_lib_path.patch && \
   patch -p1 -i $($(package)_patch_dir)/windows_lto.patch && \
diff --git a/depends/patches/qt/fix-minimum-macos.patch b/depends/patches/qt/fix-minimum-macos.patch
deleted file mode 100644
index ecaa2ca308..0000000000
--- a/depends/patches/qt/fix-minimum-macos.patch
+++ /dev/null
@@ -1,18 +0,0 @@
-Ensure that Qt handles the minimum macOS version properly
-
-This patch can be dropped for LLVM Clang 17+, after commit
-https://github.com/llvm/llvm-project/commit/c8e2dd8c6f490b68e41fe663b44535a8a21dfeab
-
-
---- a/qtbase/src/corelib/global/qsystemdetection.h
-+++ b/qtbase/src/corelib/global/qsystemdetection.h
-@@ -220,6 +220,9 @@
- #  include <Availability.h>
- #  include <AvailabilityMacros.h>
- #
-+#  undef __MAC_OS_X_VERSION_MIN_REQUIRED
-+#  define __MAC_OS_X_VERSION_MIN_REQUIRED MAC_OS_X_VERSION_MIN_REQUIRED
-+#
- #  ifdef Q_OS_MACOS
- #    if !defined(__MAC_OS_X_VERSION_MIN_REQUIRED) || __MAC_OS_X_VERSION_MIN_REQUIRED < __MAC_10_6
- #       undef __MAC_OS_X_VERSION_MIN_REQUIRED
diff --git a/depends/patches/qt/utc_from_string_no_optimize.patch b/depends/patches/qt/utc_from_string_no_optimize.patch
new file mode 100644
index 0000000000..533ef59b37
--- /dev/null
+++ b/depends/patches/qt/utc_from_string_no_optimize.patch
@@ -0,0 +1,84 @@
+Modify optimisation flags for various functions.
+This fixes non-determinism issues in the asm produced for
+these function when cross-compiling on x86_64 and aarch64 for
+the arm64-apple-darwin HOST.
+
+--- a/qtbase/src/corelib/itemmodels/qitemselectionmodel.cpp
++++ b/qtbase/src/corelib/itemmodels/qitemselectionmodel.cpp
+@@ -1078,9 +1078,9 @@ void QItemSelectionModelPrivate::_q_layoutChanged(const QList<QPersistentModelIn
+ 
+     if (hint != QAbstractItemModel::VerticalSortHint) {
+         // sort the "new" selection, as preparation for merging
+-        std::stable_sort(savedPersistentIndexes.begin(), savedPersistentIndexes.end(),
++        std::sort(savedPersistentIndexes.begin(), savedPersistentIndexes.end(),
+                          qt_PersistentModelIndexLessThan);
+-        std::stable_sort(savedPersistentCurrentIndexes.begin(), savedPersistentCurrentIndexes.end(),
++        std::sort(savedPersistentCurrentIndexes.begin(), savedPersistentCurrentIndexes.end(),
+                          qt_PersistentModelIndexLessThan);
+ 
+         // update the selection by merging the individual indexes
+@@ -1092,8 +1092,8 @@ void QItemSelectionModelPrivate::_q_layoutChanged(const QList<QPersistentModelIn
+         savedPersistentCurrentIndexes.clear();
+     } else {
+         // sort the "new" selection, as preparation for merging
+-        std::stable_sort(savedPersistentRowLengths.begin(), savedPersistentRowLengths.end());
+-        std::stable_sort(savedPersistentCurrentRowLengths.begin(), savedPersistentCurrentRowLengths.end());
++        std::sort(savedPersistentRowLengths.begin(), savedPersistentRowLengths.end());
++        std::sort(savedPersistentCurrentRowLengths.begin(), savedPersistentCurrentRowLengths.end());
+ 
+         // update the selection by merging the individual indexes
+         ranges = mergeRowLengths(savedPersistentRowLengths);
+
+--- a/qtbase/src/corelib/itemmodels/qitemselectionmodel_p.h
++++ b/qtbase/src/corelib/itemmodels/qitemselectionmodel_p.h
+@@ -76,7 +76,7 @@ public:
+     void _q_rowsAboutToBeInserted(const QModelIndex &parent, int start, int end);
+     void _q_columnsAboutToBeInserted(const QModelIndex &parent, int start, int end);
+     void _q_layoutAboutToBeChanged(const QList<QPersistentModelIndex> &parents = QList<QPersistentModelIndex>(), QAbstractItemModel::LayoutChangeHint hint = QAbstractItemModel::NoLayoutChangeHint);
+-    void _q_layoutChanged(const QList<QPersistentModelIndex> &parents = QList<QPersistentModelIndex>(), QAbstractItemModel::LayoutChangeHint hint = QAbstractItemModel::NoLayoutChangeHint);
++    __attribute__ ((optnone)) void _q_layoutChanged(const QList<QPersistentModelIndex> &parents = QList<QPersistentModelIndex>(), QAbstractItemModel::LayoutChangeHint hint = QAbstractItemModel::NoLayoutChangeHint);
+ 
+     inline void remove(QList<QItemSelectionRange> &r)
+     {
+
+--- a/qtbase/src/corelib/time/qdatetimeparser_p.h
++++ b/qtbase/src/corelib/time/qdatetimeparser_p.h
+@@ -215,7 +215,7 @@ private:
+             : value(ok == Invalid ? -1 : val), used(read), zeroes(zs), state(ok)
+             {}
+     };
+-    ParsedSection parseSection(const QDateTime &currentValue, int sectionIndex,
++    __attribute__ ((optnone)) ParsedSection parseSection(const QDateTime &currentValue, int sectionIndex,
+                                int offset, QString *text) const;
+     int findMonth(const QString &str1, int monthstart, int sectionIndex,
+                   int year, QString *monthName = nullptr, int *used = nullptr) const;
+
+--- a/qtbase/src/corelib/time/qtimezoneprivate_p.h
++++ b/qtbase/src/corelib/time/qtimezoneprivate_p.h
+@@ -191,7 +191,7 @@ public:
+     virtual ~QUtcTimeZonePrivate();
+ 
+     // Fall-back for UTC[+-]\d+(:\d+){,2} IDs.
+-    static qint64 offsetFromUtcString(const QByteArray &id);
++    static __attribute__ ((optnone)) qint64 offsetFromUtcString(const QByteArray &id);
+ 
+     QUtcTimeZonePrivate *clone() const override;
+ 
+--- a/qtbase/src/widgets/widgets/qcalendarwidget.cpp
++++ b/qtbase/src/widgets/widgets/qcalendarwidget.cpp
+@@ -329,13 +329,13 @@ class QCalendarYearValidator : public QCalendarDateSectionValidator
+ 
+ public:
+     QCalendarYearValidator();
+-    virtual Section handleKey(int key) override;
++    __attribute__ ((optnone)) virtual Section handleKey(int key) override;
+     virtual QDate applyToDate(QDate date, QCalendar cal) const override;
+     virtual void setDate(QDate date, QCalendar cal) override;
+     virtual QString text() const override;
+     virtual QString text(QDate date, QCalendar cal, int repeat) const override;
+ private:
+-    int pow10(int n);
++    __attribute__ ((optnone)) int pow10(int n);
+     int m_pos;
+     int m_year;
+     int m_oldYear;
diff --git a/src/.clang-format b/src/.clang-format
index 2e5d5c6449..f20e5ee2d4 100644
--- a/src/.clang-format
+++ b/src/.clang-format
@@ -43,5 +43,7 @@ SpacesInAngles:  false
 SpacesInContainerLiterals: true
 SpacesInCStyleCastParentheses: false
 SpacesInParentheses: false
+BreakBeforeConceptDeclarations: Always
+RequiresExpressionIndentation: OuterScope
 Standard: c++20
 UseTab:          Never
diff --git a/src/interfaces/chain.h b/src/interfaces/chain.h
index aeb3797392..328399c4ad 100644
--- a/src/interfaces/chain.h
+++ b/src/interfaces/chain.h
@@ -8,6 +8,7 @@
 #include <blockfilter.h>
 #include <common/settings.h>
 #include <primitives/transaction.h> // For CTransactionRef
+#include <util/result.h>
 
 #include <functional>
 #include <memory>
@@ -260,7 +261,7 @@ class Chain
     virtual void getPackageLimits(unsigned int& limit_ancestor_count, unsigned int& limit_descendant_count) = 0;
 
     //! Check if transaction will pass the mempool's chain limits.
-    virtual bool checkChainLimits(const CTransactionRef& tx) = 0;
+    virtual util::Result<void> checkChainLimits(const CTransactionRef& tx) = 0;
 
     //! Estimate smart fee.
     virtual CFeeRate estimateSmartFee(int num_blocks, bool conservative, FeeCalculation* calc = nullptr) = 0;
diff --git a/src/node/interfaces.cpp b/src/node/interfaces.cpp
index 2e547e8e2c..6963e928fe 100644
--- a/src/node/interfaces.cpp
+++ b/src/node/interfaces.cpp
@@ -45,6 +45,7 @@
 #include <uint256.h>
 #include <univalue.h>
 #include <util/check.h>
+#include <util/result.h>
 #include <util/signalinterrupt.h>
 #include <util/translation.h>
 #include <validation.h>
@@ -702,14 +703,13 @@ class ChainImpl : public Chain
         limit_ancestor_count = limits.ancestor_count;
         limit_descendant_count = limits.descendant_count;
     }
-    bool checkChainLimits(const CTransactionRef& tx) override
+    util::Result<void> checkChainLimits(const CTransactionRef& tx) override
     {
-        if (!m_node.mempool) return true;
+        if (!m_node.mempool) return {};
         LockPoints lp;
         CTxMemPoolEntry entry(tx, 0, 0, 0, 0, false, 0, lp);
         LOCK(m_node.mempool->cs);
-        std::string err_string;
-        return m_node.mempool->CheckPackageLimits({tx}, entry.GetTxSize(), err_string);
+        return m_node.mempool->CheckPackageLimits({tx}, entry.GetTxSize());
     }
     CFeeRate estimateSmartFee(int num_blocks, bool conservative, FeeCalculation* calc) override
     {
diff --git a/src/policy/feerate.h b/src/policy/feerate.h
index 41f4a4d06b..2e50172914 100644
--- a/src/policy/feerate.h
+++ b/src/policy/feerate.h
@@ -71,6 +71,8 @@ class CFeeRate
     friend bool operator!=(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK != b.nSatoshisPerK; }
     CFeeRate& operator+=(const CFeeRate& a) { nSatoshisPerK += a.nSatoshisPerK; return *this; }
     std::string ToString(const FeeEstimateMode& fee_estimate_mode = FeeEstimateMode::BTC_KVB) const;
+    friend CFeeRate operator*(const CFeeRate& f, int a) { return CFeeRate(a * f.nSatoshisPerK); }
+    friend CFeeRate operator*(int a, const CFeeRate& f) { return CFeeRate(a * f.nSatoshisPerK); }
 
     SERIALIZE_METHODS(CFeeRate, obj) { READWRITE(obj.nSatoshisPerK); }
 };
diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp
index 7e62d75583..c6bc5f8f1d 100644
--- a/src/script/descriptor.cpp
+++ b/src/script/descriptor.cpp
@@ -1777,15 +1777,15 @@ std::unique_ptr<DescriptorImpl> ParseScript(uint32_t& key_exp_index, Span<const
         const auto script_ctx{ctx == ParseScriptContext::P2WSH ? miniscript::MiniscriptContext::P2WSH : miniscript::MiniscriptContext::TAPSCRIPT};
         KeyParser parser(/*out = */&out, /* in = */nullptr, /* ctx = */script_ctx, key_exp_index);
         auto node = miniscript::FromString(std::string(expr.begin(), expr.end()), parser);
+        if (parser.m_key_parsing_error != "") {
+            error = std::move(parser.m_key_parsing_error);
+            return nullptr;
+        }
         if (node) {
             if (ctx != ParseScriptContext::P2WSH && ctx != ParseScriptContext::P2TR) {
                 error = "Miniscript expressions can only be used in wsh or tr.";
                 return nullptr;
             }
-            if (parser.m_key_parsing_error != "") {
-                error = std::move(parser.m_key_parsing_error);
-                return nullptr;
-            }
             if (!node->IsSane() || node->IsNotSatisfiable()) {
                 // Try to find the first insane sub for better error reporting.
                 auto insane_node = node.get();
diff --git a/src/serialize.h b/src/serialize.h
index 263b781f21..19585c630a 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -271,10 +271,9 @@ template<typename Stream> inline void Serialize(Stream& s, int32_t a ) { ser_wri
 template<typename Stream> inline void Serialize(Stream& s, uint32_t a) { ser_writedata32(s, a); }
 template<typename Stream> inline void Serialize(Stream& s, int64_t a ) { ser_writedata64(s, a); }
 template<typename Stream> inline void Serialize(Stream& s, uint64_t a) { ser_writedata64(s, a); }
-template<typename Stream, int N> inline void Serialize(Stream& s, const char (&a)[N]) { s.write(MakeByteSpan(a)); }
-template<typename Stream, int N> inline void Serialize(Stream& s, const unsigned char (&a)[N]) { s.write(MakeByteSpan(a)); }
-template <typename Stream, typename B, std::size_t N> void Serialize(Stream& s, const std::array<B, N>& a) { (void)/* force byte-type */UCharCast(a.data()); s.write(MakeByteSpan(a)); }
-template <typename Stream, typename B> void Serialize(Stream& s, Span<B> span) { (void)/* force byte-type */UCharCast(span.data()); s.write(AsBytes(span)); }
+template <typename Stream, BasicByte B, int N> void Serialize(Stream& s, const B (&a)[N]) { s.write(MakeByteSpan(a)); }
+template <typename Stream, BasicByte B, std::size_t N> void Serialize(Stream& s, const std::array<B, N>& a) { s.write(MakeByteSpan(a)); }
+template <typename Stream, BasicByte B> void Serialize(Stream& s, Span<B> span) { s.write(AsBytes(span)); }
 
 #ifndef CHAR_EQUALS_INT8
 template <typename Stream> void Unserialize(Stream&, char) = delete; // char serialization forbidden. Use uint8_t or int8_t
@@ -288,10 +287,9 @@ template<typename Stream> inline void Unserialize(Stream& s, int32_t& a ) { a =
 template<typename Stream> inline void Unserialize(Stream& s, uint32_t& a) { a = ser_readdata32(s); }
 template<typename Stream> inline void Unserialize(Stream& s, int64_t& a ) { a = ser_readdata64(s); }
 template<typename Stream> inline void Unserialize(Stream& s, uint64_t& a) { a = ser_readdata64(s); }
-template<typename Stream, int N> inline void Unserialize(Stream& s, char (&a)[N]) { s.read(MakeWritableByteSpan(a)); }
-template<typename Stream, int N> inline void Unserialize(Stream& s, unsigned char (&a)[N]) { s.read(MakeWritableByteSpan(a)); }
-template <typename Stream, typename B, std::size_t N> void Unserialize(Stream& s, std::array<B, N>& a) { (void)/* force byte-type */UCharCast(a.data()); s.read(MakeWritableByteSpan(a)); }
-template <typename Stream, typename B> void Unserialize(Stream& s, Span<B> span) { (void)/* force byte-type */UCharCast(span.data()); s.read(AsWritableBytes(span)); }
+template <typename Stream, BasicByte B, int N> void Unserialize(Stream& s, B (&a)[N]) { s.read(MakeWritableByteSpan(a)); }
+template <typename Stream, BasicByte B, std::size_t N> void Unserialize(Stream& s, std::array<B, N>& a) { s.read(MakeWritableByteSpan(a)); }
+template <typename Stream, BasicByte B> void Unserialize(Stream& s, Span<B> span) { s.read(AsWritableBytes(span)); }
 
 template <typename Stream> inline void Serialize(Stream& s, bool a) { uint8_t f = a; ser_writedata8(s, f); }
 template <typename Stream> inline void Unserialize(Stream& s, bool& a) { uint8_t f = ser_readdata8(s); a = f; }
@@ -755,18 +753,23 @@ template<typename Stream, typename T> void Serialize(Stream& os, const std::uniq
 template<typename Stream, typename T> void Unserialize(Stream& os, std::unique_ptr<const T>& p);
 
 
-
 /**
  * If none of the specialized versions above matched, default to calling member function.
  */
-template<typename Stream, typename T>
-inline void Serialize(Stream& os, const T& a)
+template <class T, class Stream>
+concept Serializable = requires(T a, Stream s) { a.Serialize(s); };
+template <typename Stream, typename T>
+    requires Serializable<T, Stream>
+void Serialize(Stream& os, const T& a)
 {
     a.Serialize(os);
 }
 
-template<typename Stream, typename T>
-inline void Unserialize(Stream& is, T&& a)
+template <class T, class Stream>
+concept Unserializable = requires(T a, Stream s) { a.Unserialize(s); };
+template <typename Stream, typename T>
+    requires Unserializable<T, Stream>
+void Unserialize(Stream& is, T&& a)
 {
     a.Unserialize(is);
 }
diff --git a/src/span.h b/src/span.h
index 2e8da27cde..2c27a54fc7 100644
--- a/src/span.h
+++ b/src/span.h
@@ -8,6 +8,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
+#include <span>
 #include <type_traits>
 
 #ifdef DEBUG
@@ -283,13 +284,16 @@ Span<std::byte> MakeWritableByteSpan(V&& v) noexcept
     return AsWritableBytes(Span{std::forward<V>(v)});
 }
 
-// Helper functions to safely cast to unsigned char pointers.
+// Helper functions to safely cast basic byte pointers to unsigned char pointers.
 inline unsigned char* UCharCast(char* c) { return reinterpret_cast<unsigned char*>(c); }
 inline unsigned char* UCharCast(unsigned char* c) { return c; }
 inline unsigned char* UCharCast(std::byte* c) { return reinterpret_cast<unsigned char*>(c); }
 inline const unsigned char* UCharCast(const char* c) { return reinterpret_cast<const unsigned char*>(c); }
 inline const unsigned char* UCharCast(const unsigned char* c) { return c; }
 inline const unsigned char* UCharCast(const std::byte* c) { return reinterpret_cast<const unsigned char*>(c); }
+// Helper concept for the basic byte types.
+template <typename B>
+concept BasicByte = requires { UCharCast(std::span<B>{}.data()); };
 
 // Helper function to safely convert a Span to a Span<[const] unsigned char>.
 template <typename T> constexpr auto UCharSpanCast(Span<T> s) -> Span<typename std::remove_pointer<decltype(UCharCast(s.data()))>::type> { return {UCharCast(s.data()), s.size()}; }
diff --git a/src/test/amount_tests.cpp b/src/test/amount_tests.cpp
index 3815a5bba6..e5ab1cfb90 100644
--- a/src/test/amount_tests.cpp
+++ b/src/test/amount_tests.cpp
@@ -85,6 +85,32 @@ BOOST_AUTO_TEST_CASE(GetFeeTest)
     BOOST_CHECK(CFeeRate(CAmount(27), 789) == CFeeRate(34));
     // Maximum size in bytes, should not crash
     CFeeRate(MAX_MONEY, std::numeric_limits<uint32_t>::max()).GetFeePerK();
+
+    // check multiplication operator
+    // check multiplying by zero
+    feeRate = CFeeRate(1000);
+    BOOST_CHECK(0 * feeRate == CFeeRate(0));
+    BOOST_CHECK(feeRate * 0 == CFeeRate(0));
+    // check multiplying by a positive integer
+    BOOST_CHECK(3 * feeRate == CFeeRate(3000));
+    BOOST_CHECK(feeRate * 3 == CFeeRate(3000));
+    // check multiplying by a negative integer
+    BOOST_CHECK(-3 * feeRate == CFeeRate(-3000));
+    BOOST_CHECK(feeRate * -3 == CFeeRate(-3000));
+    // check commutativity
+    BOOST_CHECK(2 * feeRate == feeRate * 2);
+    // check with large numbers
+    int largeNumber = 1000000;
+    BOOST_CHECK(largeNumber * feeRate == feeRate * largeNumber);
+    // check boundary values
+    int maxInt = std::numeric_limits<int>::max();
+    feeRate = CFeeRate(maxInt);
+    BOOST_CHECK(feeRate * 2 == CFeeRate(static_cast<int64_t>(maxInt) * 2));
+    BOOST_CHECK(2 * feeRate == CFeeRate(static_cast<int64_t>(maxInt) * 2));
+    // check with zero fee rate
+    feeRate = CFeeRate(0);
+    BOOST_CHECK(feeRate * 5 == CFeeRate(0));
+    BOOST_CHECK(5 * feeRate == CFeeRate(0));
 }
 
 BOOST_AUTO_TEST_CASE(BinaryOperatorTest)
diff --git a/src/test/descriptor_tests.cpp b/src/test/descriptor_tests.cpp
index f4f4e39f40..c779bf6f73 100644
--- a/src/test/descriptor_tests.cpp
+++ b/src/test/descriptor_tests.cpp
@@ -592,9 +592,9 @@ BOOST_AUTO_TEST_CASE(descriptor_test)
     CheckUnparsable("raw(and_v(vc:andor(pk(L4gM1FBdyHNpkzsFh9ipnofLhpZRp2mwobpeULy1a6dBTvw8Ywtd),pk_k(Kx9HCDjGiwFcgVNhTrS5z5NeZdD6veeam61eDxLDCkGWujvL4Gnn),and_v(v:older(1),pk_k(L4o2kDvXXDRH2VS9uBnouScLduWt4dZnM25se7kvEjJeQ285en2A))),after(10)))", "sh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(02aa27e5eb2c185e87cd1dbc3e0efc9cb1175235e0259df1713424941c3cb40402))),after(10)))", "Miniscript expressions can only be used in wsh or tr.");
     CheckUnparsable("", "tr(034D2224bbbbbbbbbbcbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb40,{{{{{{{{{{{{{{{{{{{{{{multi(1,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/967808'/9,xprvA1RpRA33e1JQ7ifknakTFNpgXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/968/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/3/4/5/58/55/2/5/58/58/2/5/5/5/8/5/2/8/5/85/2/8/2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/8/5/8/5/4/5/585/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/8/2/5/8/5/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/58/58/2/0/8/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/5/8/5/8/24/5/58/52/5/8/5/2/8/24/5/58/588/246/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/5/4/5/58/55/58/2/5/8/55/2/5/8/58/555/58/2/5/8/4//2/5/58/5w/2/5/8/5/2/4/5/58/5558'/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/8/2/5/8/5/5/8/58/2/5/58/58/2/5/8/9/588/2/58/2/5/8/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/82/5/8/5/5/58/52/6/8/5/2/8/{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{}{{{{{{{{{DDD2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8588/246/8/5/2DLDDDDDDDbbD3DDDD/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/3/4/5/58/55/2/5/58/58/2/5/5/5/8/5/2/8/5/85/2/8/2/5/8D)/5/2/5/58/58/2/5/58/58/58/588/2/58/2/5/8/5/25/58/58/2/5/58/58/2/5/8/9/588/2/58/2/6780,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFW/8/5/2/5/58678008')", "'multi(1,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/967808'/9,xprvA1RpRA33e1JQ7ifknakTFNpgXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/968/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/3/4/5/58/55/2/5/58/58/2/5/5/5/8/5/2/8/5/85/2/8/2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/8/5/8/5/4/5/585/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/8/2/5/8/5/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/58/58/2/0/8/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/5/8/5/8/24/5/58/52/5/8/5/2/8/24/5/58/588/246/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/5/4/5/58/55/58/2/5/8/55/2/5/8/58/555/58/2/5/8/4//2/5/58/5w/2/5/8/5/2/4/5/58/5558'/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/8/2/5/8/5/5/8/58/2/5/58/58/2/5/8/9/588/2/58/2/5/8/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/82/5/8/5/5/58/52/6/8/5/2/8/{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{}{{{{{{{{{DDD2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8588/246/8/5/2DLDDDDDDDbbD3DDDD/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/3/4/5/58/55/2/5/58/58/2/5/5/5/8/5/2/8/5/85/2/8/2/5/8D)/5/2/5/58/58/2/5/58/58/58/588/2/58/2/5/8/5/25/58/58/2/5/58/58/2/5/8/9/588/2/58/2/6780,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFW/8/5/2/5/58678008'' is not a valid descriptor function");
     // No uncompressed keys allowed
-    CheckUnparsable("", "wsh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(049228de6902abb4f541791f6d7f925b10e2078ccb1298856e5ea5cc5fd667f930eac37a00cc07f9a91ef3c2d17bf7a17db04552ff90ac312a5b8b4caca6c97aa4))),after(10)))", "A function is needed within P2WSH");
+    CheckUnparsable("", "wsh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(049228de6902abb4f541791f6d7f925b10e2078ccb1298856e5ea5cc5fd667f930eac37a00cc07f9a91ef3c2d17bf7a17db04552ff90ac312a5b8b4caca6c97aa4))),after(10)))", "Uncompressed keys are not allowed");
     // No hybrid keys allowed
-    CheckUnparsable("", "wsh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(069228de6902abb4f541791f6d7f925b10e2078ccb1298856e5ea5cc5fd667f930eac37a00cc07f9a91ef3c2d17bf7a17db04552ff90ac312a5b8b4caca6c97aa4))),after(10)))", "A function is needed within P2WSH");
+    CheckUnparsable("", "wsh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(069228de6902abb4f541791f6d7f925b10e2078ccb1298856e5ea5cc5fd667f930eac37a00cc07f9a91ef3c2d17bf7a17db04552ff90ac312a5b8b4caca6c97aa4))),after(10)))", "Hybrid public keys are not allowed");
     // Insane at top level
     CheckUnparsable("wsh(and_b(vc:andor(pk(L4gM1FBdyHNpkzsFh9ipnofLhpZRp2mwobpeULy1a6dBTvw8Ywtd),pk_k(Kx9HCDjGiwFcgVNhTrS5z5NeZdD6veeam61eDxLDCkGWujvL4Gnn),and_v(v:older(1),pk_k(L4o2kDvXXDRH2VS9uBnouScLduWt4dZnM25se7kvEjJeQ285en2A))),after(10)))", "wsh(and_b(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(02aa27e5eb2c185e87cd1dbc3e0efc9cb1175235e0259df1713424941c3cb40402))),after(10)))", "and_b(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(02aa27e5eb2c185e87cd1dbc3e0efc9cb1175235e0259df1713424941c3cb40402))),after(10)) is invalid");
     // Invalid sub
diff --git a/src/test/fuzz/minisketch.cpp b/src/test/fuzz/minisketch.cpp
index a17be73f6c..698cb15fc9 100644
--- a/src/test/fuzz/minisketch.cpp
+++ b/src/test/fuzz/minisketch.cpp
@@ -12,14 +12,27 @@
 #include <map>
 #include <numeric>
 
-using node::MakeMinisketch32;
+namespace {
+
+Minisketch MakeFuzzMinisketch32(size_t capacity, uint32_t impl)
+{
+    return Assert(Minisketch(32, impl, capacity));
+}
+
+} // namespace
 
 FUZZ_TARGET(minisketch)
 {
     FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
+
     const auto capacity{fuzzed_data_provider.ConsumeIntegralInRange<size_t>(1, 200)};
-    Minisketch sketch_a{Assert(MakeMinisketch32(capacity))};
-    Minisketch sketch_b{Assert(MakeMinisketch32(capacity))};
+    const uint32_t impl{fuzzed_data_provider.ConsumeIntegralInRange<uint32_t>(0, Minisketch::MaxImplementation())};
+    if (!Minisketch::ImplementationSupported(32, impl)) return;
+
+    Minisketch sketch_a{MakeFuzzMinisketch32(capacity, impl)};
+    Minisketch sketch_b{MakeFuzzMinisketch32(capacity, impl)};
+    sketch_a.SetSeed(fuzzed_data_provider.ConsumeIntegral<uint64_t>());
+    sketch_b.SetSeed(fuzzed_data_provider.ConsumeIntegral<uint64_t>());
 
     // Fill two sets and keep the difference in a map
     std::map<uint32_t, bool> diff;
@@ -47,8 +60,11 @@ FUZZ_TARGET(minisketch)
     }
     const auto num_diff{std::accumulate(diff.begin(), diff.end(), size_t{0}, [](auto n, const auto& e) { return n + e.second; })};
 
-    Minisketch sketch_ar{MakeMinisketch32(capacity)};
-    Minisketch sketch_br{MakeMinisketch32(capacity)};
+    Minisketch sketch_ar{MakeFuzzMinisketch32(capacity, impl)};
+    Minisketch sketch_br{MakeFuzzMinisketch32(capacity, impl)};
+    sketch_ar.SetSeed(fuzzed_data_provider.ConsumeIntegral<uint64_t>());
+    sketch_br.SetSeed(fuzzed_data_provider.ConsumeIntegral<uint64_t>());
+
     sketch_ar.Deserialize(sketch_a.Serialize());
     sketch_br.Deserialize(sketch_b.Serialize());
 
diff --git a/src/test/fuzz/process_message.cpp b/src/test/fuzz/process_message.cpp
index acb03ac5fc..56b391ed5c 100644
--- a/src/test/fuzz/process_message.cpp
+++ b/src/test/fuzz/process_message.cpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2020-2022 The Bitcoin Core developers
+// Copyright (c) 2020-present The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -8,9 +8,6 @@
 #include <primitives/transaction.h>
 #include <protocol.h>
 #include <script/script.h>
-#include <serialize.h>
-#include <span.h>
-#include <streams.h>
 #include <sync.h>
 #include <test/fuzz/FuzzedDataProvider.h>
 #include <test/fuzz/fuzz.h>
@@ -20,13 +17,10 @@
 #include <test/util/net.h>
 #include <test/util/setup_common.h>
 #include <test/util/validation.h>
-#include <util/chaintype.h>
 #include <util/check.h>
 #include <util/time.h>
-#include <validation.h>
 #include <validationinterface.h>
 
-#include <atomic>
 #include <cstdlib>
 #include <iostream>
 #include <memory>
@@ -81,8 +75,7 @@ FUZZ_TARGET(process_message, .init = initialize_process_message)
 
     CSerializedNetMsg net_msg;
     net_msg.m_type = random_message_type;
-    // fuzzed_data_provider is fully consumed after this call, don't use it
-    net_msg.data = fuzzed_data_provider.ConsumeRemainingBytes<unsigned char>();
+    net_msg.data = ConsumeRandomLengthByteVector(fuzzed_data_provider, MAX_PROTOCOL_MESSAGE_LENGTH);
 
     connman.FlushSendBuffer(p2p_node);
     (void)connman.ReceiveMsgFrom(p2p_node, std::move(net_msg));
diff --git a/src/test/fuzz/process_messages.cpp b/src/test/fuzz/process_messages.cpp
index 3f722f60ee..6b264907b5 100644
--- a/src/test/fuzz/process_messages.cpp
+++ b/src/test/fuzz/process_messages.cpp
@@ -16,7 +16,6 @@
 #include <test/util/net.h>
 #include <test/util/setup_common.h>
 #include <test/util/validation.h>
-#include <util/chaintype.h>
 #include <util/time.h>
 #include <validationinterface.h>
 
@@ -72,7 +71,7 @@ FUZZ_TARGET(process_messages, .init = initialize_process_messages)
 
         CSerializedNetMsg net_msg;
         net_msg.m_type = random_message_type;
-        net_msg.data = ConsumeRandomLengthByteVector(fuzzed_data_provider);
+        net_msg.data = ConsumeRandomLengthByteVector(fuzzed_data_provider, MAX_PROTOCOL_MESSAGE_LENGTH);
 
         CNode& random_node = *PickValue(fuzzed_data_provider, peers);
 
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index b783181bb8..acee56fe78 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -196,25 +196,20 @@ util::Result<CTxMemPool::setEntries> CTxMemPool::CalculateAncestorsAndCheckLimit
     return ancestors;
 }
 
-bool CTxMemPool::CheckPackageLimits(const Package& package,
-                                    const int64_t total_vsize,
-                                    std::string &errString) const
+util::Result<void> CTxMemPool::CheckPackageLimits(const Package& package,
+                                                  const int64_t total_vsize) const
 {
     size_t pack_count = package.size();
 
     // Package itself is busting mempool limits; should be rejected even if no staged_ancestors exist
     if (pack_count > static_cast<uint64_t>(m_limits.ancestor_count)) {
-        errString = strprintf("package count %u exceeds ancestor count limit [limit: %u]", pack_count, m_limits.ancestor_count);
-        return false;
+        return util::Error{Untranslated(strprintf("package count %u exceeds ancestor count limit [limit: %u]", pack_count, m_limits.ancestor_count))};
     } else if (pack_count > static_cast<uint64_t>(m_limits.descendant_count)) {
-        errString = strprintf("package count %u exceeds descendant count limit [limit: %u]", pack_count, m_limits.descendant_count);
-        return false;
+        return util::Error{Untranslated(strprintf("package count %u exceeds descendant count limit [limit: %u]", pack_count, m_limits.descendant_count))};
     } else if (total_vsize > m_limits.ancestor_size_vbytes) {
-        errString = strprintf("package size %u exceeds ancestor size limit [limit: %u]", total_vsize, m_limits.ancestor_size_vbytes);
-        return false;
+        return util::Error{Untranslated(strprintf("package size %u exceeds ancestor size limit [limit: %u]", total_vsize, m_limits.ancestor_size_vbytes))};
     } else if (total_vsize > m_limits.descendant_size_vbytes) {
-        errString = strprintf("package size %u exceeds descendant size limit [limit: %u]", total_vsize, m_limits.descendant_size_vbytes);
-        return false;
+        return util::Error{Untranslated(strprintf("package size %u exceeds descendant size limit [limit: %u]", total_vsize, m_limits.descendant_size_vbytes))};
     }
 
     CTxMemPoolEntry::Parents staged_ancestors;
@@ -224,8 +219,7 @@ bool CTxMemPool::CheckPackageLimits(const Package& package,
             if (piter) {
                 staged_ancestors.insert(**piter);
                 if (staged_ancestors.size() + package.size() > static_cast<uint64_t>(m_limits.ancestor_count)) {
-                    errString = strprintf("too many unconfirmed parents [limit: %u]", m_limits.ancestor_count);
-                    return false;
+                    return util::Error{Untranslated(strprintf("too many unconfirmed parents [limit: %u]", m_limits.ancestor_count))};
                 }
             }
         }
@@ -236,8 +230,8 @@ bool CTxMemPool::CheckPackageLimits(const Package& package,
     const auto ancestors{CalculateAncestorsAndCheckLimits(total_vsize, package.size(),
                                                           staged_ancestors, m_limits)};
     // It's possible to overestimate the ancestor/descendant totals.
-    if (!ancestors.has_value()) errString = "possibly " + util::ErrorString(ancestors).original;
-    return ancestors.has_value();
+    if (!ancestors.has_value()) return util::Error{Untranslated("possibly " + util::ErrorString(ancestors).original)};
+    return {};
 }
 
 util::Result<CTxMemPool::setEntries> CTxMemPool::CalculateMemPoolAncestors(
diff --git a/src/txmempool.h b/src/txmempool.h
index bac7a445d6..9da51756e6 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -605,11 +605,10 @@ class CTxMemPool
      *                                          to mempool. The transactions need not be direct
      *                                          ancestors/descendants of each other.
      * @param[in]       total_vsize             Sum of virtual sizes for all transactions in package.
-     * @param[out]      errString               Populated with error reason if a limit is hit.
+     * @returns {} or the error reason if a limit is hit.
      */
-    bool CheckPackageLimits(const Package& package,
-                            int64_t total_vsize,
-                            std::string &errString) const EXCLUSIVE_LOCKS_REQUIRED(cs);
+    util::Result<void> CheckPackageLimits(const Package& package,
+                                          int64_t total_vsize) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /** Populate setDescendants with all in-mempool descendants of hash.
      *  Assumes that setDescendants includes all in-mempool descendants of anything
diff --git a/src/validation.cpp b/src/validation.cpp
index c706e8e03a..4af3b3a7ae 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -52,6 +52,7 @@
 #include <util/hasher.h>
 #include <util/moneystr.h>
 #include <util/rbf.h>
+#include <util/result.h>
 #include <util/signalinterrupt.h>
 #include <util/strencodings.h>
 #include <util/time.h>
@@ -1025,10 +1026,10 @@ bool MemPoolAccept::PackageMempoolChecks(const std::vector<CTransactionRef>& txn
     assert(std::all_of(txns.cbegin(), txns.cend(), [this](const auto& tx)
                        { return !m_pool.exists(GenTxid::Txid(tx->GetHash()));}));
 
-    std::string err_string;
-    if (!m_pool.CheckPackageLimits(txns, total_vsize, err_string)) {
+    auto result = m_pool.CheckPackageLimits(txns, total_vsize);
+    if (!result) {
         // This is a package-wide error, separate from an individual transaction error.
-        return package_state.Invalid(PackageValidationResult::PCKG_POLICY, "package-mempool-limits", err_string);
+        return package_state.Invalid(PackageValidationResult::PCKG_POLICY, "package-mempool-limits", util::ErrorString(result).original);
     }
    return true;
 }
diff --git a/src/wallet/spend.cpp b/src/wallet/spend.cpp
index e97e658f38..b51cd6332f 100644
--- a/src/wallet/spend.cpp
+++ b/src/wallet/spend.cpp
@@ -1296,8 +1296,9 @@ static util::Result<CreatedTransactionResult> CreateTransactionInternal(
 
     if (gArgs.GetBoolArg("-walletrejectlongchains", DEFAULT_WALLET_REJECT_LONG_CHAINS)) {
         // Lastly, ensure this tx will pass the mempool's chain limits
-        if (!wallet.chain().checkChainLimits(tx)) {
-            return util::Error{_("Transaction has too long of a mempool chain")};
+        auto result = wallet.chain().checkChainLimits(tx);
+        if (!result) {
+            return util::Error{util::ErrorString(result)};
         }
     }
 
diff --git a/src/wallet/test/fuzz/coinselection.cpp b/src/wallet/test/fuzz/coinselection.cpp
index ade3ec3f60..87d419493b 100644
--- a/src/wallet/test/fuzz/coinselection.cpp
+++ b/src/wallet/test/fuzz/coinselection.cpp
@@ -86,7 +86,6 @@ FUZZ_TARGET(coinselection)
     const CFeeRate effective_fee_rate{ConsumeMoney(fuzzed_data_provider, /*max=*/COIN)};
     // Discard feerate must be at least dust relay feerate
     const CFeeRate discard_fee_rate{fuzzed_data_provider.ConsumeIntegralInRange<CAmount>(DUST_RELAY_TX_FEE, COIN)};
-    const CAmount min_viable_change{ConsumeMoney(fuzzed_data_provider, /*max=*/COIN)};
     const CAmount target{fuzzed_data_provider.ConsumeIntegralInRange<CAmount>(1, MAX_MONEY)};
     const bool subtract_fee_outputs{fuzzed_data_provider.ConsumeBool()};
 
@@ -95,12 +94,15 @@ FUZZ_TARGET(coinselection)
     coin_params.m_subtract_fee_outputs = subtract_fee_outputs;
     coin_params.m_long_term_feerate = long_term_fee_rate;
     coin_params.m_effective_feerate = effective_fee_rate;
-    coin_params.min_viable_change = min_viable_change;
-    coin_params.change_output_size = fuzzed_data_provider.ConsumeIntegralInRange<int>(10, 1000);
+    coin_params.change_output_size = fuzzed_data_provider.ConsumeIntegralInRange(1, MAX_SCRIPT_SIZE);
     coin_params.m_change_fee = effective_fee_rate.GetFee(coin_params.change_output_size);
     coin_params.m_discard_feerate = discard_fee_rate;
     coin_params.change_spend_size = fuzzed_data_provider.ConsumeIntegralInRange<int>(41, 1000);
-    coin_params.m_cost_of_change = coin_params.m_change_fee + coin_params.m_discard_feerate.GetFee(coin_params.change_spend_size);
+    const auto change_spend_fee{coin_params.m_discard_feerate.GetFee(coin_params.change_spend_size)};
+    coin_params.m_cost_of_change = coin_params.m_change_fee + change_spend_fee;
+    CScript change_out_script = CScript() << std::vector<unsigned char>(coin_params.change_output_size, OP_TRUE);
+    const auto dust{GetDustThreshold(CTxOut{/*nValueIn=*/0, change_out_script}, coin_params.m_discard_feerate)};
+    coin_params.min_viable_change = std::max(change_spend_fee + 1, dust);
 
     int next_locktime{0};
     CAmount total_balance{CreateCoins(fuzzed_data_provider, utxo_pool, coin_params, next_locktime)};
@@ -119,7 +121,7 @@ FUZZ_TARGET(coinselection)
     auto result_bnb = coin_params.m_subtract_fee_outputs ? util::Error{Untranslated("BnB disabled when SFFO is enabled")} :
                       SelectCoinsBnB(group_pos, target, coin_params.m_cost_of_change, MAX_STANDARD_TX_WEIGHT);
     if (result_bnb) {
-        assert(result_bnb->GetChange(coin_params.m_cost_of_change, CAmount{0}) == 0);
+        assert(result_bnb->GetChange(coin_params.min_viable_change, coin_params.m_change_fee) == 0);
         assert(result_bnb->GetSelectedValue() >= target);
         (void)result_bnb->GetShuffledInputVector();
         (void)result_bnb->GetInputSet();
diff --git a/test/functional/wallet_basic.py b/test/functional/wallet_basic.py
index 4a5397bb85..c8ef570b1c 100755
--- a/test/functional/wallet_basic.py
+++ b/test/functional/wallet_basic.py
@@ -640,7 +640,7 @@ def run_test(self):
 
         node0_balance = self.nodes[0].getbalance()
         # With walletrejectlongchains we will not create the tx and store it in our wallet.
-        assert_raises_rpc_error(-6, "Transaction has too long of a mempool chain", self.nodes[0].sendtoaddress, sending_addr, node0_balance - Decimal('0.01'))
+        assert_raises_rpc_error(-6, f"too many unconfirmed ancestors [limit: {chainlimit * 2}]", self.nodes[0].sendtoaddress, sending_addr, node0_balance - Decimal('0.01'))
 
         # Verify nothing new in wallet
         assert_equal(total_txs, len(self.nodes[0].listtransactions("*", 99999)))