Windows 10 reached EOS (end of support) on October 14, 2025. If you are on Windows 10, see this article.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More
Solved Archived

Cannot reset using "How to reset the default user agent on Firefox"

no.cache

Just to clarify, the solution is not AV related. Use this REFRESH BUTTON. Backup first. It takes a few minutes so be patient.

This is my first attempt to create a custom User Style for [Firefox 48.0b9] and I've messed it up to the point that even a RESET + clearing all HISTORY + CACHE doesn't work.  :(

Just to clarify, the solution is not AV related. Use this [https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save|REFRESH REFRESH BUTTON]. Backup first. It takes a few minutes so be patient. This is my first attempt to create a custom User Style for [Firefox 48.0b9] and I've messed it up to the point that even a RESET + clearing all HISTORY + CACHE doesn't work. :(

no.cache மூலமாக திருத்தப்பட்டது

Read this answer in context

தீர்வு தேர்ந்தெடுக்கப்பட்டது

You did not include that in the original post.

https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save

Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

All Replies (5)

Excuse me, those steps are exactly what I performed. Did you even read my lead post? Are there additional steps? Where?

no.cache மூலமாக திருத்தப்பட்டது

merry widow said

even a RESET + clearing all HISTORY + CACHE doesn't work.  :(

how-reset-default-user-agent-firefox said

type about:config and press Enter . . . .

That is what I did. Are you playing with me?

தீர்வு தேர்ந்தெடுக்கப்பட்டது

You did not include that in the original post.

https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save

Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.