--- a/devtools/client/locales/en-US/webconsole.properties
+++ b/devtools/client/locales/en-US/webconsole.properties
@@ -44,16 +44,20 @@ timeEnd=%1$S: %2$Sms
 # call to console.clear() to let the user know the previous messages of the
 # console have been removed programmatically.
 consoleCleared=Console was cleared.
 
 # LOCALIZATION NOTE (noCounterLabel): this string is used to display
 # count-messages with no label provided.
 noCounterLabel=<no label>
 
+# LOCALIZATION NOTE (counterDoesntExist): this string is displayed when
+# console.countReset() is called with a counter that doesn't exist.
+counterDoesntExist=Counter “%S” doesn't exist.
+
 # LOCALIZATION NOTE (noGroupLabel): this string is used to display
 # console.group messages with no label provided.
 noGroupLabel=<no group label>
 
 # LOCALIZATION NOTE (Autocomplete.blank): this string is used when inputnode
 # string containing anchor doesn't matches to any property in the content.
 Autocomplete.blank=  <- no result
 

--- a/devtools/client/webconsole/test/components/console-api-call.test.js
+++ b/devtools/client/webconsole/test/components/console-api-call.test.js
@@ -197,16 +197,22 @@ describe("ConsoleAPICall component:", ()
         key: "console.count | default: 3",
         expectedBodyText: "default: 3",
       }, {
         key: "console.count | default: 4",
         expectedBodyText: "default: 4",
       }, {
         key: "console.count | test counter: 3",
         expectedBodyText: "test counter: 3",
+      }, {
+        key: "console.countReset | test counter: 0",
+        expectedBodyText: "test counter: 0",
+      }, {
+        key: "console.countReset | counterDoesntExist",
+        expectedBodyText: "Counter “test counter” doesn't exist.",
       }];
 
       for (const {key, expectedBodyText} of messages) {
         const message = stubPreparedMessages.get(key);
         const wrapper = render(ConsoleApiCall({ message, serviceContainer }));
 
         expect(wrapper.find(".message-body").text()).toBe(expectedBodyText);
       }

--- a/devtools/client/webconsole/test/fixtures/stub-generators/stub-snippets.js
+++ b/devtools/client/webconsole/test/fixtures/stub-generators/stub-snippets.js
@@ -152,26 +152,30 @@ consoleApi.set("console.count", {
     "console.count | default: 1",
     "console.count | default: 2",
     "console.count | test counter: 1",
     "console.count | test counter: 2",
     "console.count | default: 3",
     "console.count | clear",
     "console.count | default: 4",
     "console.count | test counter: 3",
+    "console.countReset | test counter: 0",
+    "console.countReset | counterDoesntExist",
   ],
   code: `
     console.count();
     console.count();
     console.count("test counter");
     console.count("test counter");
     console.count();
     console.clear();
     console.count();
     console.count("test counter");
+    console.countReset("test counter");
+    console.countReset("test counter");
 `});
 
 // CSS messages
 const cssMessage = new Map();
 
 cssMessage.set("Unknown property", `
 p {
   such-unknown-property: wow;

--- a/devtools/client/webconsole/test/fixtures/stubs/consoleApi.js
+++ b/devtools/client/webconsole/test/fixtures/stubs/consoleApi.js
@@ -1616,16 +1616,68 @@ stubPreparedMessages.set(`console.count 
   "exceptionDocURL": null,
   "userProvidedStyles": [],
   "notes": null,
   "indent": 0,
   "prefix": "",
   "private": false
 }));
 
+stubPreparedMessages.set(`console.countReset | test counter: 0`, new ConsoleMessage({
+  "id": "1",
+  "allowRepeating": true,
+  "source": "console-api",
+  "timeStamp": 1526920412190,
+  "type": "log",
+  "helperType": null,
+  "level": "log",
+  "messageText": "test counter: 0",
+  "parameters": null,
+  "repeatId": "{\"frame\":{\"source\":\"http://example.com/browser/devtools/client/webconsole/test/fixtures/stub-generators/test-console-api.html\",\"line\":10,\"column\":5},\"groupId\":null,\"indent\":0,\"level\":\"log\",\"messageText\":\"test counter: 0\",\"parameters\":null,\"source\":\"console-api\",\"type\":\"log\",\"userProvidedStyles\":[],\"private\":false}",
+  "stacktrace": null,
+  "frame": {
+    "source": "http://example.com/browser/devtools/client/webconsole/test/fixtures/stub-generators/test-console-api.html",
+    "line": 10,
+    "column": 5
+  },
+  "groupId": null,
+  "exceptionDocURL": null,
+  "userProvidedStyles": [],
+  "notes": null,
+  "indent": 0,
+  "prefix": "",
+  "private": false
+}));
+
+stubPreparedMessages.set(`console.countReset | counterDoesntExist`, new ConsoleMessage({
+  "id": "1",
+  "allowRepeating": true,
+  "source": "console-api",
+  "timeStamp": 1526920412191,
+  "type": "log",
+  "helperType": null,
+  "level": "warn",
+  "messageText": "Counter “test counter” doesn't exist.",
+  "parameters": null,
+  "repeatId": "{\"frame\":{\"source\":\"http://example.com/browser/devtools/client/webconsole/test/fixtures/stub-generators/test-console-api.html\",\"line\":11,\"column\":5},\"groupId\":null,\"indent\":0,\"level\":\"warn\",\"messageText\":\"Counter “test counter” doesn't exist.\",\"parameters\":null,\"source\":\"console-api\",\"type\":\"log\",\"userProvidedStyles\":[],\"private\":false}",
+  "stacktrace": null,
+  "frame": {
+    "source": "http://example.com/browser/devtools/client/webconsole/test/fixtures/stub-generators/test-console-api.html",
+    "line": 11,
+    "column": 5
+  },
+  "groupId": null,
+  "exceptionDocURL": null,
+  "userProvidedStyles": [],
+  "notes": null,
+  "indent": 0,
+  "prefix": "",
+  "private": false
+}));
+
 stubPackets.set(`console.log('foobar', 'test')`, {
   "from": "server1.conn0.child1/consoleActor2",
   "type": "consoleAPICall",
   "message": {
     "addonId": "",
     "arguments": [
       "foobar",
       "test"
@@ -3133,12 +3185,68 @@ stubPackets.set(`console.count | test co
     "timeStamp": 1511365913335,
     "timer": null,
     "workerType": "none",
     "styles": [],
     "category": "webdev"
   }
 });
 
+stubPackets.set(`console.countReset | test counter: 0`, {
+  "from": "server1.conn0.child1/consoleActor2",
+  "type": "consoleAPICall",
+  "message": {
+    "addonId": "",
+    "arguments": [
+      "test counter"
+    ],
+    "columnNumber": 5,
+    "counter": {
+      "count": 0,
+      "label": "test counter"
+    },
+    "filename": "http://example.com/browser/devtools/client/webconsole/test/fixtures/stub-generators/test-console-api.html",
+    "functionName": "triggerPacket",
+    "groupName": "",
+    "level": "countReset",
+    "lineNumber": 10,
+    "prefix": "",
+    "private": false,
+    "timeStamp": 1526920412190,
+    "timer": null,
+    "workerType": "none",
+    "styles": [],
+    "category": "webdev"
+  }
+});
+
+stubPackets.set(`console.countReset | counterDoesntExist`, {
+  "from": "server1.conn0.child1/consoleActor2",
+  "type": "consoleAPICall",
+  "message": {
+    "addonId": "",
+    "arguments": [
+      "test counter"
+    ],
+    "columnNumber": 5,
+    "counter": {
+      "error": "counterDoesntExist",
+      "label": "test counter"
+    },
+    "filename": "http://example.com/browser/devtools/client/webconsole/test/fixtures/stub-generators/test-console-api.html",
+    "functionName": "triggerPacket",
+    "groupName": "",
+    "level": "countReset",
+    "lineNumber": 11,
+    "prefix": "",
+    "private": false,
+    "timeStamp": 1526920412191,
+    "timer": null,
+    "workerType": "none",
+    "styles": [],
+    "category": "webdev"
+  }
+});
+
 module.exports = {
   stubPreparedMessages,
   stubPackets,
 };

--- a/devtools/client/webconsole/utils/messages.js
+++ b/devtools/client/webconsole/utils/messages.js
@@ -78,23 +78,28 @@ function transformConsoleAPICallPacket(p
 
   // Special per-type conversion.
   switch (type) {
     case "clear":
       // We show a message to users when calls console.clear() is called.
       parameters = [l10n.getStr("consoleCleared")];
       break;
     case "count":
+    case "countReset":
       // Chrome RDP doesn't have a special type for count.
       type = MESSAGE_TYPE.LOG;
       let {counter} = message;
 
       if (!counter) {
         // We don't show anything if we don't have counter data.
         type = MESSAGE_TYPE.NULL_MESSAGE;
+      } else if (counter.error) {
+        messageText = l10n.getFormatStr(counter.error, [counter.label]);
+        level = MESSAGE_LEVEL.WARN;
+        parameters = null;
       } else {
         let label = counter.label ? counter.label : l10n.getStr("noCounterLabel");
         messageText = `${label}: ${counter.count}`;
         parameters = null;
       }
       break;
     case "time":
       parameters = null;