Hello! Since some days I have the problem that all files I download from outlook are accompanied by a preceding UTF-8 in the file name. This is not the case for e.g. google chrome. Can I fix this problem by myself, or is it a general problem of firefox 128.9esr (64-bit)?

Did you try with Firefox in Troubleshoot Mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#search What OS? If windows, home or pro, and what security software besides MS Defender are you running?

I just tried on Linux and also seeing the issue. see screenshot I'm running 137.0.2 Here's what I see in the console, but someone from Dev will have to chime in.

I think Microsoft made a change a few days ago. Apparently Chrome/Edge are able to understand the new syntax but Firefox/Safari are not.

Another thread here on SUMO:

https://support.mozilla.org/questions/1507363

Bug report I filed today:

https://bugzilla.mozilla.org/show_bug.cgi?id=1961710

If you like, you can add yourself to the CC list and keep an eye on whether they ask for more testing.

Thank you for your replies. In order to specify: I have a Linux Slackware 15.0 operation system, so it has probably nothing to do with Microsoft. I wait for that this thread is read by somebody from the firefox development and will be repaired in an upcoming new version.

Sorry, I meant that Microsoft made a change to Outlook, not your OS.

As an emergency workaround, I added a patch for this to my Content-Type Fixer extension. In case you want to try it:

https://addons.mozilla.org/firefox/addon/content-type-fixer/

To turn it on, click its hammer button. When you're done with it, click again and choose Stop Listening.

@jscher2000: no problem at all. Yes, outlook seems to be changed very often - some functionality I am used to does no longer work, but that's another story (still, I do not know how to contact the outlook team concerning these). Thank you for building this fixer. I will try it, though I have only a hand full files downloaded each day which I can fix by hand. Still, I hope that someone of the firefox development fixes this permanently. And it is a problem of firefox (maybe caused by a change in outlook), as it does not exist with google chrome.

This issue should be fixed in version 138.0.1