Two versions of FF need to be installed? 26 and 27
I'm using Win 8. I was looking at Programs, and saw that I had two versions of Firefox installed, 26 and 27.
I un-installed 26 (because I had 27), and then, when I went to launch FF, I got the error message: "Could not load XPCOM," and, it wanted to delete the Shortcut.
I did a System Restore - and that didn't fix it.
I downloaded the current version of FF, 27.0.1, installed over what had been Restored, and that fixed it.
Isn't it confusing to have more than one version of the browser installed?
Chosen solution
If you installed over it, then the previous version has been replaced.
If you're running the 32-bit version of Windows 8 and you have an English (US) version of Firefox, then the aforementioned registry key is the one you want to delete:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Mozilla Firefox 27.0.1 (x86 en-US)Read this answer in context 👍 0
All Replies (7)
You almost certainly only had one version of Firefox installed. Sometimes, program uninstallation entries are not properly removed¹. When clicking such an old entry, you are in fact uninstalling the current version.
You can manually remove such entries from the registry. Exercise caution when using the registry editor; you may want to back up the parent key first by right-clicking it and choosing Export.
For example, the uninstallation entry for the current version, English (US) locale can be found in the following locations:
- 32-bit Windows:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Mozilla Firefox 27.0.1 (x86 en-US)
- 64-bit Windows:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\Mozilla Firefox 27.0.1 (x86 en-US)
System Restore tends to make a mess of things². It should be saved as a last resort measure in case of severe system problems. It's good that you ran the installer again to fix any issues it may have caused.
¹ http://support.microsoft.com/kb/314481
² https://bugzilla.mozilla.org/show_bug.cgi?id=702045
I run my anti-virus once a week, and set a Restore Point afterwards, so I know I have a good Restore point.
I'd say that I use System Restore, 3 or 4 times a year, and have never noticed anything bad.
Just this one time, though, I messed up something with the Win 8 install, and went back to a Restore Point. I noticed that there was something like 30-40 GB of space being used for no reason. I forget how I determined this. Anyway, I clicked around, and found out how you use Disk Cleanup to take care of it - make sure to click on "Clean up system files" - and that took care of it.
I just installed 28.0, and see that 27.0.1 is there.
28.0 installed over 27.0.1
Did 28.0 un-install 27.0.1, and just not accurately reflect this in the Registry?
Chosen Solution
If you installed over it, then the previous version has been replaced.
If you're running the 32-bit version of Windows 8 and you have an English (US) version of Firefox, then the aforementioned registry key is the one you want to delete:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Mozilla Firefox 27.0.1 (x86 en-US)
Worked . . . 27.0.1 is gone
. . . Why doesn't the over-write of the new version do this, since it un-installs it?
. . . It un-installs the previous version - everything - but leaves it showing as installed? What's the logic behind this? Thx.
The old registry key is normally removed automatically. Something went wrong in your case. I don't know what or why; I can only tell you that it can happen with any program, not just Firefox.
I've only ever noticed it now with Firefox . . . and maybe some Microsoft C+++ or something, but maybe multiple copies of that need to be there, idk.
It seems like it happens if you update, and write over a previous version.