--- a/devtools/client/webconsole/new-console-output/test/store/messages.test.js
+++ b/devtools/client/webconsole/new-console-output/test/store/messages.test.js
@@ -563,16 +563,28 @@ describe("Message reducer:", () => {
       const { dispatch, getState } = setupStore();
 
       const packet = stubPackets.get("console.dirxml(window)");
       dispatch(actions.messagesAdd([packet]));
 
       const dirxmlMessage = getLastMessage(getState());
       expect(dirxmlMessage.level).toEqual(MESSAGE_TYPE.LOG);
     });
+
+    it("does not throw when adding incomplete console.count packet", () => {
+      const { dispatch, getState } = setupStore();
+      const packet = clonePacket(stubPackets.get(`console.count('bar')`));
+
+      // Remove counter information to mimick packet we receive in the browser console.
+      delete packet.message.counter;
+
+      dispatch(actions.messagesAdd([packet]));
+      // The message should not be added to the state.
+      expect(getAllMessagesById(getState()).size).toBe(0);
+    });
   });
 
   describe("expandedMessageIds", () => {
     it("opens console.trace messages when they are added", () => {
       const { dispatch, getState } = setupStore();
 
       const message = stubPackets.get("console.trace()");
       dispatch(actions.messagesAdd([message]));

--- a/devtools/client/webconsole/new-console-output/utils/messages.js
+++ b/devtools/client/webconsole/new-console-output/utils/messages.js
@@ -81,19 +81,25 @@ function transformConsoleAPICallPacket(p
     case "clear":
       // We show a message to users when calls console.clear() is called.
       parameters = [l10n.getStr("consoleCleared")];
       break;
     case "count":
       // Chrome RDP doesn't have a special type for count.
       type = MESSAGE_TYPE.LOG;
       let {counter} = message;
-      let label = counter.label ? counter.label : l10n.getStr("noCounterLabel");
-      messageText = `${label}: ${counter.count}`;
-      parameters = null;
+
+      if (!counter) {
+        // We don't show anything if we don't have counter data.
+        type = MESSAGE_TYPE.NULL_MESSAGE;
+      } else {
+        let label = counter.label ? counter.label : l10n.getStr("noCounterLabel");
+        messageText = `${label}: ${counter.count}`;
+        parameters = null;
+      }
       break;
     case "time":
       parameters = null;
       if (timer && timer.error) {
         messageText = l10n.getFormatStr(timer.error, [timer.name]);
         level = MESSAGE_LEVEL.WARN;
       } else {
         // We don't show anything for console.time calls to match Chrome's behaviour.