Firefox catches a cold

Yesterday I upgraded to Firefox 1.5.0.1. Everything seemed fine. This morning though I can’t open any window without getting this error message:

XML Parsing Error: no element found
Location: chrome://browser/content/browser.xul
Line Number 1, Column 1:

Surprisingly even reinstalling Firefox doesn’t help. Neither does rebooting the machine. However logging in as a different user does fix the problem and allow me to run Firefox, but when I log back in as my usual self I get this error message again. That suggests it’s a preferences problem. I hid the Library/Mozilla folder but that didn’t fix anything. Let’s try hiding Library/Preferences/org.mozilla.firefox.plist. Nope, that doesn’t fix anything either.

Ah, wait a minute. The Firefox preferences aren’t the same place the Mozilla prefs are. They’re in Library/Application Support/Firefox instead of Library/Mozilla. Let’s try getting rid of that. Ok. That seems to have something to do with it. Now Firefox will start. Surprisingly after the moving the old Profile back, everything works again. I can’t explain it; but the solution to this problem seems to be:

1. Quit Firefox
2. Rename Library/Application Support/Firefox to Library/Application Support/Firefox2
3. Launch Firefox
4. Quit Firefox
5. Move Library/Application Support/Firefox to the trash
6. Rename Library/Application Support/Firefox2 to Library/Application Support/Firefox
7. Launch Firefox

Oops. That fix appears to be only temporary. Now it’s doing it again. OK. Let’s think about the error message for a minute. What is it telling me? It appears to say that in the file browser/content/browser.xul there’s no root element. (Side note: I can probably figure this out, but there’s no excuse for showing this message to an end user. You shouldn’t need to have written a dozen books about XML just to use a web browser.) Where might that be? I don’t see any such file, but I do see that the Profile contains a chrome folder. This contains an overlayinfo folder, which contains browser folder, which contains a content folder. However this does not contain a browser.xul file. Maybe it’s missing? Once again, let’s try renaming the Firefox folder, so it will create a new profile.

Hmm, that did not create the missing file; but it didn’t create overlayinfo/browser/content either? Maybe I can just delete that folder. Let’s hide it and see what happens. Nothing. Same problem as before.

Oh wait. Looks like there are more chrome directories in the extensions folder. Let’s try hiding them. OK, that seems to have worked. Will it stick? Yes, I can quit and relaunch Firefox. And adding them back reproduces the problem. So I’m reasonably confident I’ve isolated the problem to the extensions.

The next obvious question is which extension caused the problem. I have quite a few: Web Developer, AdBlock, XForms, Sage, Tab Downloader, GreaseMonkey, and Customize Google. I could try adding them back one by one, but I don’t really have the energy for that right now. I will keep an eye on this in the future.

Anyone have any idea what’s going on here? This bug might be relevant, but then again might not be. I’ve filed my own bug addressing the user interface issues, leaving aside the root cause of the problem.

This entry was posted on Friday, February 3rd, 2006 at 6:18 AM and is filed under Web Development. You can follow any responses to this entry through the Atom feed. You can make a comment, Digg this story, or trackback from your own site.