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Can not get any add-ons to install on Firefox past the initial installation verification.

  • 3 replies
  • 2 have this problem
  • 9 views
  • Last reply by FredMcD

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I go to Add-ons Manager then to get add-ons. I pick the add-on Ad Block and select it and a pop-up window appears. It says Firefox prevented this site to install software on your computer. I pressed the allow button and then it does not go past the Downloading and Verifying add-on task. It freezes and will not continue. This happens on other add-ons that I have tried to load.

I go to Add-ons Manager then to get add-ons. I pick the add-on Ad Block and select it and a pop-up window appears. It says Firefox prevented this site to install software on your computer. I pressed the allow button and then it does not go past the Downloading and Verifying add-on task. It freezes and will not continue. This happens on other add-ons that I have tried to load.

Chosen solution

Where were you trying to download the add-ons from? Mozilla Add-ons Web Page {web link}


Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options)
key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

Read this answer in context 👍 1

All Replies (3)

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Chosen Solution

Where were you trying to download the add-ons from? Mozilla Add-ons Web Page {web link}


Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options)
key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

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Thanks so much for start in safe mode suggestion. It worked and I'm back in business. Many Thanks FredMcD and All The Best.

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Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes). If the problem goes away, that tells us one thing. If it does not, that tells us something else.


It could be the work of one of your add-ons. Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control>(Mac=<Command>)<Shift> A)

In the Add-ons Manager, on the left, select Extensions. Disable a few add-ons, then Restart Firefox.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All of them.

If the problem continues, disable some more (restarting FF). Continue until the problem is gone. After, you know what group is causing the issue. Re-enable the last group ONE AT A TIME (restarting FF) until the problem returns.

Once you think you found the problem, disable that and re-enable all the others, then restart again. Let us know who the suspect is, detective.