mixpanel-flutter Uncaught MissingPluginException after deploying web version

Hi guys, I was using mixpanel in flutter web. When I am testing it in local, it is working fine but when I deployed it on firebase hosting, it started throwing error on Mixpanel.init() with the error "Uncaught MissingPluginException(No implementation found for method initialize on channel mixpanel_flutter)" & causing the app not be load. So please check this as it is blocking our release.

Oct 04 '22 13:10 tejHackerDEV

Check your code in index.html

<head>
    // ~~~
    <script src="flutter.js" defer></script>
    <script src="./assets/packages/mixpanel_flutter/assets/mixpanel.js"></script>
</head>

It should be written END LINE OF HEAD.

Dec 26 '22 08:12 LOCKEDFILE

I am having the same issue. My script tag is in the correct place in index.html

the package is working fine locally (in debug)

But when I deploy using firebase hosting it is throwing this error: Uncaught MissingPluginException(No implementation found for method initialize on channel mixpanel_flutter)

Jan 17 '23 04:01 DamDam98

I am having this same problem in Flutter 3.10.2 with version 2.1.1.

In local environment it works correctly, but when deploying on Google App Engine the same error occurs: Uncaught MissingPluginException(No implementation found for method initialize on channel mixpanel_flutter)

pubspec.yaml: mixpanel_flutter: ^2.1.1 # https://pub.dev/packages/mixpanel_flutter

index.html (at the end):

<head>
   ...
  <script src="./assets/packages/mixpanel_flutter/assets/mixpanel.js"></script>
</head>

Jun 16 '23 08:06 jemutorres

For me the error was: PlatformException: Cannot read properties of undefined (reading 'init'), null, null). Adding this to index.html fix the issue for both release and debug builds:

<head>
   ...
  <script src="./assets/packages/mixpanel_flutter/assets/mixpanel.js"></script>
</head>

Jun 17 '23 19:06 jomonson

PlatformException: Cannot read properties of undefined (reading 'init'), null, null) is caused by a missing script tag, but MissingPluginException(No implementation found for method initialize on channel mixpanel_flutter) occurs even with the tag in place.

https://github.com/mixpanel/mixpanel-flutter/issues/91 suggests that the error occurs due to ad blockers, but I have the same issue even if all ad blockers are disabled and all calls to the mixpanel CDN returns 200. Both in chrome and firefox.