hi, are you using avast/avg as security software on the affected system? a recent update of their webshield component is using the policy feature, injecting a certificate into firefox which is triggering the master password request currently (you could check if that's the case by entering about:policies into the firefox address bar).

that issue will receive a fix in the upcoming firefox 67.0 that's due to be released next week.

Hi philipp, I use Norton Security Suite & MBAM Premium. I checked about:policies and nothing was active. I've tried pretty much everything. My biggest concern was that maybe there was some kind of security issue. I recently had two unauthorized access attempts to my online bank account. I can't seem to find anything linking to anything else. I'll wait for the new release to see if that fixes the problem.

Thanks for the help.

are you using firefox sync?

No. Nothing is synced.

hm, i don't have any immediate clues what would be triggering it then... what are your startup settings - restoring the last session, displaying the firefox default homepage or a custom one? does starting in safe mode cause any different behaviour?

The dialog opens when I normally startup to the Firefox default homepage. When I start in safe mode or use a desktop shortcut the dialog doesn't appear.

I just changed Homepage & new windows to blank page. Closed Firefox and opened again. Password dialog shows up with that, also.

does your norton security software contain a password manager addon for firefox?

If it has a password manager I don't use it. Norton Family is not configured and there is no settings password.

can you take a look under the menu > addons > extensions section if there's "norton identity safe" listed there... (if yes, please disable it when you're not using it) - i'm mainly suggesting that because you said safemode didn't produce that behaviour.

I never installed any Norton products on Firefox. The only extensions are AdGuard Adblocker (disabled) and Flash Video Downloader (disabled). I added those last night.

any change when you refresh firefox - that would reset most stuff to the default configuration, but keep bookmarks, passwords and history: Refresh Firefox - reset add-ons and settings

No dialog appears on the first startup after a refresh. After I personalize the settings the dialog appears.

any change when disabling the master password, restarting and then reenabling it?

No. The dialog appears when I start again.

I'm considering an uninstall/reinstall of Firefox but that wouldn't tell us where the issue is.

I removed my Master Password and I cleaned out everything with CCleaner - including stored passwords.

Then I completed another refresh.

I walked through each page of the options one at a time and closed and re-opened FF each time. Everything is restored, except for my passwords, and the Master Password dialog hasn't shown up until I signed in to here.

One thing that I did notice. When I refreshed before, the Widevine Content Decryption Module never installed. This time I got tired of waiting after about half an hour and I simply disabled it.

I'll re-enter my passwords and I'll leave the AdGuard extension uninstalled.

I'll let you know if anything changes.

AdGuard for Windows was the culprit. (Not the extension.)

Following the issue with extensions the other night I tried AdGuard for Windows. It wasn't until I refreshed Firefox today that other issues started happening and the culprit revealed itself. After uninstalling AdGuard and refreshing Firefox again the problem is gone.

(I discovered another issue today with IE11 storing usernames and passwords even though you tell it 'Not For This Site'. They imported into Firefox and when I checked Windows Credentials they didn't show up. I tried an import from Edge and they were there, also. I posted on the MS Forum about this.)

Anyway, thanks for all of your help. I'm good here.

great, thank you for following up with the solution you've found!