Firefox fails to launch after upgrade: says mozglue.dll missing
Firefox was working perfectly on my Win7x64 laptop until I installed the upgrade to 29.0.1. It installed successfully (standard install, no custom options). "Launch now" from the installer launched Firefx successfully, but thereafter all attempts to launch Firefox result in the "mozglue.dll is not on your computer" error message. I verified that mozglue.dll is correctly installed. I retried the download and install a dozen times; still fails. I totally wiped the previous version including user preferences then clean installed. Still fails. I manually ran regedit and removed all traces of Mozilla, Firefox and Netscape Navigator tags and values. Rebooted a dozen times. Still fails. I manually added the path to the PATH variable. Still fails. With each install attempt, Firefox launches fine from the installer but not thereafter. I tried launching from commandline with -safe-mode. Still fails. I did a full virus and malware scan. Did a registry cleanup. Did everything I can think of to tr to troubleshoot this. I successfully installed and can run IE and Chrome browsers. Nothing else on my PC is affected and no other browsers or programs have any problems. Then I tried downgrading to v27 again. It gives the same error. Seems like this is specific to Firefox.
Failing some solution, I'm forced to permenantly move to one of the other browsers that work. Sorry.
Wšykne wótegrona (1)
Hi dwneumann, Thank you for your question, I understand that since updating to 29.0.1 there are have been a number of issues. However there have been updates to version 33.1.1 that have had some serious security fixes. I would recommend doing a clean install of the newest version of Firefox for your system.
Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:
Note: You might want to print these steps or view them in another browser.
- Download the latest Desktop version of Firefox from mozilla.org (or choose the download for your operating system and language from this page) and save the setup file to your computer.
- After the download finishes, close all Firefox windows (or open the Firefox menu
and click the close button 
).
- Delete the Firefox installation folder, which is located in one of these locations, by default:
- Windows:
- C:\Program Files\Mozilla Firefox
- C:\Program Files (x86)\Mozilla Firefox
- Mac: Delete Firefox from the Applications folder.
- Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
- Windows:
- Now, go ahead and reinstall Firefox:
- Double-click the downloaded installation file and go through the steps of the installation wizard.
- Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.
More information about reinstalling Firefox can be found here.
WARNING: Do not use a third party uninstaller as part of this process. Doing so could permanently delete your Firefox profile data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot be easily recovered unless they have been backed up to an external device! See Back up and restore information in Firefox profiles.
Please report back to say if this helped you!
Thank you.