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javascript console?

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I was playing a browser based game and it popped up with the error saying:

an error occured running the unity content on this page. See your Javascript console for more info. The error was: InvalidStateError. A mutation operation was attempted on a database that did not allow mutations.

uh... what? I have no idea what Unity is or does. I have no idea (even looking here), how to open Javascript console, and I simply loaded the page. How did a mutation operation, whatever that is, occur?

Anyone have any idea what that means or how to fix it? If so, I'd appreciate any help.

I was playing a browser based game and it popped up with the error saying: an error occured running the unity content on this page. See your Javascript console for more info. The error was: InvalidStateError. A mutation operation was attempted on a database that did not allow mutations. uh... what? I have no idea what Unity is or does. I have no idea (even looking here), how to open Javascript console, and I simply loaded the page. How did a mutation operation, whatever that is, occur? Anyone have any idea what that means or how to fix it? If so, I'd appreciate any help.

Chosen solution

Does this happen repeatedly?

I suggest clearing Firefox's cache and trying again: How to clear the Firefox cache. (If you have a large hard drive, this might take a few minutes to finish.)

You also could look at this storage test page to see whether it reports any storage problems in your Firefox. Note that it's normal for the third and fourth tests to fail in private windows, but they should all pass in regular (non-private) windows:

https://firefox-storage-test.glitch.me/

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Chosen Solution

Does this happen repeatedly?

I suggest clearing Firefox's cache and trying again: How to clear the Firefox cache. (If you have a large hard drive, this might take a few minutes to finish.)

You also could look at this storage test page to see whether it reports any storage problems in your Firefox. Note that it's normal for the third and fourth tests to fail in private windows, but they should all pass in regular (non-private) windows:

https://firefox-storage-test.glitch.me/