diff --git a/ethers-providers/src/provider.rs b/ethers-providers/src/provider.rs
index 7d36041b5..6b5727d66 100644
--- a/ethers-providers/src/provider.rs
+++ b/ethers-providers/src/provider.rs
@@ -574,8 +574,14 @@ impl<P: JsonRpcClient> Middleware for Provider<P> {
         block: Option<BlockId>,
     ) -> Result<U256, ProviderError> {
         let tx = utils::serialize(tx);
-        let block = utils::serialize(&block.unwrap_or_else(|| BlockNumber::Latest.into()));
-        self.request("eth_estimateGas", [tx, block]).await
+        // Some chains (e.g. Optimism) don't support a block ID being passed as a param,
+        // so refrain from defaulting to BlockNumber::Latest.
+        let params = if let Some(block_id) = block {
+            vec![tx, utils::serialize(&block_id)]
+        } else {
+            vec![tx]
+        };
+        self.request("eth_estimateGas", params).await
     }
 
     async fn create_access_list(
diff --git a/ethers-providers/src/transports/quorum.rs b/ethers-providers/src/transports/quorum.rs
index eecbcc653..8bc776817 100644
--- a/ethers-providers/src/transports/quorum.rs
+++ b/ethers-providers/src/transports/quorum.rs
@@ -227,6 +227,7 @@ impl<T: JsonRpcClientWrapper> QuorumProvider<T> {
             "eth_getStorageAt" |
             "eth_getCode" |
             "eth_getProof" |
+            "eth_estimateGas" |
             "trace_call" |
             "trace_block" => {
                 // calls that include the block number in the params at the last index of json array
@@ -401,7 +402,7 @@ impl<T> WeightedProvider<T> {
 #[derive(Error, Debug)]
 /// Error thrown when sending an HTTP request
 pub enum QuorumError {
-    #[error("No Quorum reached.")]
+    #[error("No Quorum reached. (Values: {:?}, Errors: {:?})", values, errors)]
     NoQuorumReached { values: Vec<Value>, errors: Vec<ProviderError> },
 }