diff --git a/assets/src/modules/config/LayerTree.js b/assets/src/modules/config/LayerTree.js
index 58480fec3d..588dd5cab1 100644
--- a/assets/src/modules/config/LayerTree.js
+++ b/assets/src/modules/config/LayerTree.js
@@ -413,7 +413,12 @@ function buildLayerTreeGroupConfigItems(wmsCapaLayerGroup, layersCfg, level) {
         const wmsName = wmsCapaLayer.Name;
         const cfg = layersCfg.getLayerConfigByWmsName(wmsName);
         if (cfg == null) {
-            console.log('The WMS layer name `'+ wmsName +'` is unknown!');
+            const errorMessage = `The WMS layer name "${wmsName}" is unknown. Is the Lizmap configuration file "${lizUrls.params.project}.qgs.cfg" up to date ?`;
+            console.warn(errorMessage);
+
+            if (document && document.body.dataset.lizmapAdminUser === 1) {
+                lizMap.addMessage(errorMessage, 'warning', true).attr('id', 'lizmap-warning-message');
+            }
             continue;
         }
         if (wmsCapaLayer.hasOwnProperty('Layer') && wmsCapaLayer.Layer.length != 0) {