Hi, it is possible that your ad-blockers or security software is stopping the install. Please try Safe Mode if you have any ad-blockers as I have no information sent to me that would tell me. SAFE MODE

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

In Firefox Safe mode these changes are effective:

• all extensions are disabled (about:addons)
• default theme is used (no persona)
• userChrome.css and userContent.css are ignored (chrome folder)
• default toolbar layout is used (file: localstore-safe.rdf)
• Javascript JIT compilers are disabled (prefs: javascript.options.*jit)
• hardware acceleration is disabled (Options > Advanced > General)
• plugins are not affected
• preferences are not affected

TEST''''is issue still there ? Try to disable your Firewall or A/V as There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connections and send their own certificate and interfere with a lot.

If any of the above is not the case please try : uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files , C:\Program Files(x86) & C:\ProgramData Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do :

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Reinstall with Current Release Firefox 59.0.2 with a Full Version Installer

• https://www.mozilla.org/firefox/all/

Please let us know if this solved your issue or if need further assistance.

Hi Pkshadow,

Thank you for reply, I appreciate all the helpful advice!

Unfortunately, my add-ons issue persists.  : (

1. I tried Firefox in safe mode.

2. I disabled Nortons Security, both AV and Firewall. Checked Firefox program permissions and were set to ALLOW.

3. Uninstalled Firefox successfully. Strangely, there was nothing left of Firefox in Program Files, Program Files (x86) or ProgramData for me to delete.

4. Did Disk Cleanup & System Files cleanup - not much there as I use CCleaner and Norton maintenance regularly for years.

5. Installed a fresh copy of Firefox 59.0.02 with Full Version installer and without making any changes, I tried to install the add-on "NoScript". Still getting the same error message. Next I tried the add-on "Google translate" with the same result.

6. Looked at programs installed end March/early April and thought the 2 programs found might have been causing the issue. Uninstalled both and rebooted. Attempted to install add-ons again. Still the same error.

Currently, Firefox is running without a single add-on and forced to use Microsoft Edge after almost 14 years with Firefox. Eeek.

I am now thinking that the culprit is Firefox version 59.0.02 which also installed around end of March/early April... and so I would like to go back to version 58.0 which worked perfectly for me, but I can't find a download location for the old version. Can you help me with a download location of version 58.0?

Before starting my troubleshooting, I created a restore point, so if the older version doesn't fix the issue, I will go back to restore point 59.0.02 with add-ons that still work, but can't be updated, and hope that a new Firefox version will fix this.

Thank you, again!

It’s possible that there is a problem with the file(s) that store the extensions registry.

Type about:support in the address bar and press enter.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Delete all extensions files and compatibility.ini in the Firefox profile folder to reset the extensions registry.

• https://support.mozilla.org/kb/Profiles

New files will be created when required.

After, restart Firefox.

See "Corrupt extension files":

• http://kb.mozillazine.org/Unable_to_install_themes_or_extensions
• https://support.mozilla.org/kb/Unable+to+install+add-ons

+++++++++++++++++++++++++++ You will have to approve the updating one last time.

Hi FredMcD,

Thank you for your suggestion, unfortunately I am still unable to download/install Extensions.

Haven't been able to find a download location for Firefox 58.0.02 (not 59.0.02 typed in error above) so after your suggestion didn't work, I decided to use the system restore point I'd created prior to my troubleshooting thinking I would get Firefox back with the previously installed add-ons that worked, though I wouldn't be able to update them.

Sadly, I discovered that system restore does NOT save BOOKMARKS or Browser EXTENSIONS.  : (

I couldn't find the F/profile copy I'd saved just prior to new installation of Firefox with refresh (maybe refresh was a mistake), but I did find an old bookmarks backup dated last year, Mar 2017, so manged to at least get most of them back.

Not sure what else to do aside from continuing to look for 58.0.02, the last Firefox version where extensions worked perfectly.

Thank you.

@ barneybears,

Would you check in your Window Settings => Apps :

Make sure you have it set to 'Allow all apps'

(It's a mere stab in the dark, but worth a try .... )

Install Older Version Of Firefox {web link} Be sure to read everything here.

If you still want to downgrade, look under; I still want to downgrade. Click the Directory of other versions and languages link. Look for the directory of the version that you want. But, remember that old versions may have security issues.

You should also check out Firefox; Extended Support Release {web link} ESR Notes System Requirements

Hi Murphy,

I appreciate your suggestion which was worth looking into. I checked permissions for apps - it was set to allow. : ( So I continued with troubleshooting.

Thank you.

Hi, I did give you this info for a reason so would do before working on issue.

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Also if still on 59.0.2 are 1 version 0.3 and now 60 came out yesterday. Help --> About to update.

Have you tried to create a new Profile : Profile : Make a new one and test ...:

• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

If is your Profile :

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Hi FredMcD,

Troubleshooting the inability to install/update add-ons got me into serious trouble that had me working for many days & hours on the problems, hence my lengthy silence on this thread.

1. Restoring from the system restore point I'd created prior to uninstalling and deleting Firefox Folders in C:\Program Files , C:\Program Files(x86) & C:\ProgramData and then re-installing Firefox with Refresh (as mentioned earlier) deleted my bookmarks and Add-ons that were already installed. It took me a whole day to realize that the system restore also messed up Norton security and made it totally unresponsive.

For anyone running Norton Security wishing to create or restore from a system restore point must first read this article:

https://support.norton.com/sp/en/us/home/current/solutions/v51118464_EndUserProfile_en_us

In the meantime, Windows Defender took over and provided some security with 1 way firewall protection. I also experienced some problems with Windows Defender that were caused by the Norton Security lockup.

1. I tried to uninstall Norton Security from program and features as well as from Norton Security uninstaller, but both unresponsive. 2. I used Revo uninstaller which was also unable to help. 3. I run Norton Power Eraser which didn't help. 4. I installed Norton Security from a disc which means I ended up with 2 Norton programs, restarted and finally had a partly responsive Norton Security. 5. I used the uninstaller of the 2nd installed N/S version to uninstall. 6. I used NRnR (Norton Remove and Reinstall) and finally had fresh working Norton Security. Phew...

Then I looked at sorting Firefox troubles...

Thank you for the download link to Firefox version 58.0.02, which I wanted to try out as it was the version when my install/update of Add-ons worked perfectly. Unfortunately, this didn't fix the Add-ons problem, so I uninstalled and installed the newest version (59.0.3) that had been released during the last few days. This also didn't fix the Add-ons problem but staying with this version as the most secure.

Next, I hunted around for the "Old Firefox Data" folder that had been created during Firefox install and refresh, and which had disappeared after the system restore. I was ecstatic when found buried in documents. : ))

Not entirely sure of all steps taken from here.... but I remember that on 5th May I creating a new Firefox profile, opened the file and pasted into it all files copied from the Old Firefox Data folder (pasted old data over new data) and restarted. Happy to report that I got back ALL my Bookmarks and Add-ons, though I still could not install/update add-ons.

With add-ons restored, I was able to narrow down that whatever was causing the add-ons problem occurred between 2 - 12 April.

On the 5th May, I had the add-ons problem but today, 10th May, I tested add-ons again and thrilled to see that I can install new add-ons and old add-ons are updating!!!

I am aware that between 2 -12 April some Windows updates seemed to be causing several problems. I am also aware that during the last few days there have been some major Windows updates, as well as a Norton patch, which makes me think the problem was due to a Windows update or a Norton download.

I hope my lengthy post will prove helpful to others having a similar problem with add-ons. In the end, I would have been better off waiting to see whether future windows/norton updates or patch would fix the problem.

My sincere thanks to all that replied to my post offering assistance!

That was very good, and hard work. Well done. Please flag your last post as Solved Problem so others will know.

If you ever have issues with Norton, use these links; https://support.norton.com

http://community.norton.com/

Hi Pkshadow,

Just saw your latest reply... I'd been working on my post, on and off during last 2 hours.

I followed ALL your instructions in your earlier post, but messed up big time when that didn't work, and I did system restore while running Norton.

I think I will wait a few days before updating to Firefox 60... just in case.  : )

I much appreciate all your help with detailed instructions!