Firefox must be incorrectly handling MIME types.

Any reason why not update to the latest Firefox 81?

I have installed Firefox 69.0 on a Windows Sandbox to test and had no problems. I suppose the corporate policy is interfering with some MIME types and causing some scripts to break. 

Fair enough, let's leave it at that then.

Had the same issue last night on work PC while on VPN.

Just got it now, FF 80.0.1

thewabbit:

 

Just got it now, FF 80.0.1

 

Did it resolve the issue? I would suspect not

Linux:

 

thewabbit:

 

Just got it now, FF 80.0.1

 

 

Did it resolve the issue? I would suspect not

 

I think @thewabbit means he got the same Download as behaviour, not that he got an update to FX 80 (different from OP).

Happens to me as well. Running Firefox 79.0. On a corporate image so can't update.

I know we are behind Fortinet Fortiguard web filtering, not sure if that would be causing it.

littlehead:

 

Happens to me as well. Running Firefox 79.0. On a corporate image so can't update.

 

I know we are behind Fortinet Fortiguard web filtering, not sure if that would be causing it.

 

Interesting - I'm pretty sure we're behind Fortinet too.

I saw it this afternoon with FF 80.0.1, updated to 81.0 and haven't seen it (yet?).

Just updated to 81 from 80.0.1 and no re-occurrence so far.

This happened to me twice last night using Samsung Internet on Android (Chromium)

CrashAndBurn:

 

Just updated to 81 from 80.0.1 and no re-occurrence so far.

 

Spoke too soon. The minute I hit post reply and the page refreshed I got the pop-up.

Also getting it now and then on my steam web browser: 

(Mozilla/5.0 (Windows; U; Windows NT 10.0; en-US; Valve Steam GameOverlay/1599174997; ) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.117 Safari/537.36)

Not getting it on my other browsers though.