diff --git a/package-lock.json b/package-lock.json
index fac8cd2c7ef..b57dee08341 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -229,7 +229,7 @@
                 "webpack-cli": "^5.1.4"
             },
             "engines": {
-                "vscode": "^1.101.0"
+                "vscode": "^1.100.0"
             },
             "optionalDependencies": {
                 "fsevents": "^2.3.2"
diff --git a/package.json b/package.json
index 9f3a85705ec..91e8bf0fd3e 100644
--- a/package.json
+++ b/package.json
@@ -29,7 +29,7 @@
         "theme": "light"
     },
     "engines": {
-        "vscode": "^1.101.0"
+        "vscode": "^1.100.0"
     },
     "l10n": "./l10n",
     "extensionKind": [
diff --git a/src/kernels/execution/cellExecutionMessageHandler.ts b/src/kernels/execution/cellExecutionMessageHandler.ts
index 7b136309471..8672ef263c3 100644
--- a/src/kernels/execution/cellExecutionMessageHandler.ts
+++ b/src/kernels/execution/cellExecutionMessageHandler.ts
@@ -496,6 +496,14 @@ export class CellExecutionMessageHandler implements IDisposable {
             this.execution?.start(this.startTime);
             logger.debug(`Kernel acknowledged execution of cell ${this.cell.index} @ ${this.startTime}`);
         }
+        if (!msg.header) {
+            try {
+                // eslint-disable-next-line @typescript-eslint/no-explicit-any
+                logger.warn(`Got a message without a header ${JSON.stringify(msg)}`);
+            } catch {
+                logger.warn(`Got a message without a header, no idea what it is`, msg);
+            }
+        }
 
         // eslint-disable-next-line @typescript-eslint/no-require-imports
         const jupyterLab = require('@jupyterlab/services') as typeof import('@jupyterlab/services');
@@ -527,7 +535,16 @@ export class CellExecutionMessageHandler implements IDisposable {
         } else if (jupyterLab.KernelMessage.isCommCloseMsg(msg)) {
             // Noop.
         } else {
-            logger.warn(`Unknown message ${msg.header.msg_type} : hasData=${'data' in msg.content}`);
+            if (msg.header) {
+                logger.warn(`Unknown message ${msg.header.msg_type} : hasData=${'data' in msg.content}`);
+            } else {
+                try {
+                    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+                    logger.warn(`Unknown message ${JSON.stringify(msg)}`);
+                } catch {
+                    logger.warn(`Unknown message, no idea what it is`, msg);
+                }
+            }
         }
 
         // Set execution count, all messages should have it