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?
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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)Læs dette svar i sammenhæng 👍 0
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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?
Valgt løsning
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.