What is the error message that you're getting and under what circumstances?

If you think that a Firefox program file (xul.dll) has become corrupted, you can reinstall the program files WITHOUT without removing your data, perhaps after backing up your data. However, I'm not sure that is indicated in this case because I'm not aware of any reason for this file to have gotten corrupted.

Regarding versions, why are you running Firefox 40?

For tips on backing up your profile folder -- the location of your valuable Firefox data -- see: Back up and restore information in Firefox profiles.

See also:

• https://support.mozilla.org/kb/get-latest-version-firefox-windows-xp-vista

My bad. I thought I had put in what caused the error msg. Using PrimoPDF for printing. There had been about 3 crashes in a row and so the last time I looked at the "more info" tab, saw the problem file.

Since then, next restart, problem seems to have resolved. STILL don't have the answer yet as to where I can get a single file instead of the entire program. If one file is corrupted, WHY is it necessary to re-do all???? If only one part of your roof gets wind damage, do you replace ALL of it? Or simply make the repair.

As to why I'm not using a later version, last "upgrades" on two computers caused problems such that it took me a week to get things back to where I could actually USE the browsers. I don't remember all the problems, have put them out of my mind. But one thing I do not like is the Big Brother attitude of arbitrarily disabling extensions without even letting me KNOW! Taking away my choice! To keep them or not. If FF had those needed functions built in in the first place, we wouldn't have the need for those extensions.

The latest, 44, will not allow any choice at all. I will NOT upgrade to it. At least until all the bugs are worked out. I certainly cannot afford to lose a week of work and suffer all the frustration as I already have.

I would appreciate the knowledge of where I can get individual files to replace corrupted ones. If that cannot be forthcoming, then mark this closed as I will NOT be upgrading (downgrading) or "refreshing" or reinstalling.

Hi notagains, Firefox 47 is the current version and there is an internal setting you can switch to allow unverified extensions. That might no longer be possible in Firefox 48, but it's not a reason to stick with Firefox 40.

STILL don't have the answer yet as to where I can get a single file instead of the entire program. If one file is corrupted, WHY is it necessary to re-do all???? If only one part of your roof gets wind damage, do you replace ALL of it? Or simply make the repair.

Who's going to pay for that? Mozilla already posts hundreds of installers for different languages of Firefox on different operating systems. The components of these installers are a matched set. If a "roofer" wants to extract individual files and offer them to you for individual download, you can look to them for support on potential issues that may ensue.

You can use a "Zip" file utility program like 7-Zip to open the Firefox Setup.exe installer using "Open Archive" and the extract the contents of the /Core/ folder to view the individual files.

I agree that Firefox not warning in advance what addons will be disabled is annoying.

I am sure it could be possible to at least offer an option to postpone or reverse an update for a few days to give users a chance to find a workaround or alternative.

On the whole though I agree using up to date versions of Firefox is sensible and safer than not doing so. The future change preventing most ordinary users from using insecure unapproved addons will prevent a lot

If your main issue is that you use an old version for printing have you considered installing both versions ? Then use the:

• Secure version for online browsing.
• Old insecure version for printing without connecting to the internet.

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