Windows 10 reached EOS (end of support) on October 14, 2025. For more information, see this article.

Hilfe durchsuchen

Vorsicht vor Support-Betrug: Wir fordern Sie niemals auf, eine Telefonnummer anzurufen, eine SMS an eine Telefonnummer zu senden oder persönliche Daten preiszugeben. Bitte melden Sie verdächtige Aktivitäten über die Funktion „Missbrauch melden“.

Weitere Informationen

When downloading from Outlook on the web using Firefox ESR, an unnecessary string is added to the file name.

Weitere Optionen

When accessing Outlook (https://outlook.office.com) using Firefox ESR version 128.9.0 and attempting to download a file attached to an email, the string 'UTF-8' is automatically inserted at the beginning of the file name, which is causing issues. This phenomenon does not occur with other browsers such as Edge or Chrome.

Is there a way to solve this problem?

When accessing Outlook (https://outlook.office.com) using Firefox ESR version 128.9.0 and attempting to download a file attached to an email, the string 'UTF-8' is automatically inserted at the beginning of the file name, which is causing issues. This phenomenon does not occur with other browsers such as Edge or Chrome. Is there a way to solve this problem?

Ausgewählte Lösung

I'm looking at this in Firefox 137.0.2. For a file named

Voucher - MAIKOYA.PDF

Firefox shows that the server is sending this header:

content-disposition: attachment; filename*=UTF-8''Voucher%20-%20MAIKOYA.pdf

Now, that seems a bit weird, compared to the usual format --

content-disposition: attachment; filename="Voucher - MAIKOYA.pdf"

-- but the MDN article on Content-Disposition implies that this is one of the normal options, so Firefox should know how to handle it. https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Content-Disposition#syntax

Since I can't tell whether Microsoft is doing anything at odds with the web standard, I filed a new bug:

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

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

Diese Antwort im Kontext lesen 👍 4

Alle Antworten (3)

Weitere Optionen

Ausgewählte Lösung

I'm looking at this in Firefox 137.0.2. For a file named

Voucher - MAIKOYA.PDF

Firefox shows that the server is sending this header:

content-disposition: attachment; filename*=UTF-8''Voucher%20-%20MAIKOYA.pdf

Now, that seems a bit weird, compared to the usual format --

content-disposition: attachment; filename="Voucher - MAIKOYA.pdf"

-- but the MDN article on Content-Disposition implies that this is one of the normal options, so Firefox should know how to handle it. https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Content-Disposition#syntax

Since I can't tell whether Microsoft is doing anything at odds with the web standard, I filed a new bug:

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

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

Weitere Optionen

Thank you, jscher2000. I have gained a better understanding of this issue. I will also keep an eye on the progress of the bug report. I will close this question now.

Weitere Optionen

In follow-up searching, I saw reports that Safari also doesn't understand the new Content-Disposition headers from Outlook. Even if Microsoft doesn't care about Firefox users, maybe they'll roll it back to reduce the impact on Safari users. Fingers crossed.