“An error occured running the Unity content on this page. See your browser’s JavaScript console for more info. The error was:
uncaught exception: 22525400”
We were testing Unity WebGL on Firefox and it happened while loading a new scene.
Trying building project in Development Mode from within Unity, and look at the error in the Javascript console (in Firefox that’s “Tools->Web Developer->Web Console”). It should give you more details what’s actually causing the exception.