Erasing any directory there will stop it from updating.
about:preferences -> advanced -> updates should be set "never check for updates" as well
This may be necessary for various updates, which are being added to Firefox which are screwing things up. Not sure if and when it will stabilize, so freezing updates become necessary.
Here is a further bit of info on downgrading if the updates happen anyway.
Note that from Server 2003, which is similar to XP to later versions, which have a C:\user directory, and stores profiles there, the updates are not present in the profiles directory. Where they are, is still not known.
1Go to the Firefox install guide. This page has information on how you can download an old version of Firefox. Since the link to access the page with old versions of Firefox is constantly updated, you'll have to access it from this page.
Scroll down to the "I still want to downgrade" section. It's about halfway down the page.
Click . This link is below the yellow Firefox warning box that's in the "I still want to downgrade" section. Clicking it will take you to a list of all Firefox versions.
Select a version number. Click a number on this page to go to the download page for that version of Firefox.
- For example: you would click 45.1.0esr/ to go to the download page for Firefox version 45.1.0.
Select your operating system's folder. Since the folders here aren't clearly labeled, here's how to identify your operating system's folder:
- Windows - Look for "win32/" (32-bit Windows) or "win64/" (64-bit Windows) in the link text. If you don't know your computer's bit number, check it first.
- Mac - Look for "mac/" in the link text.
Select the language folder. The list on this page is abbreviated regional languages. Select the one that matches your region. For example, if you speak English and are in the United States, you would click the "en-US/" folder.
Click the download link. This will prompt your selected version of Firefox to begin downloading to your computer.
- Depending on your browser settings, you may be prompted to confirm the download or select a location to save to before the download will begin.
Double-click the Firefox setup file. Once the download has finished, double-click the setup file to begin the installation process. On Windows, this will be an application (EXE) file, while Mac users will double-click the Firefox DMG file.
- On a MacOS Sierra and later, you may have to manually allow the installation before continuing.
- On Windows, you may be prompted to click Extract all first. If so, click Extract all, then open the extracted (non-ZIP) folder and double-click the Firefox application again.