The “Password Protection” feature of AVG security software has caused logins and passwords stored in Firefox to disappear after recent updates to Firefox. It may also cause users to experience disruptions in syncing devices as they may get logged-out repeatedly from their Firefox account, even if you do not store logins and passwords.

Note: Mozilla plans to release an add-on to address this issue. This article will be updated when the add-on is available.

Affected Firefox versions:

Release 67.0.2
Beta 68.0b9 and up
Nightly versions since 6/7/19

By now AVG should have an update available to their software which stops further problems with passwords and logins in Firefox. The fix by AVG is in virus definition 19061402 and higher.

First make sure that AVG is up-to-date, so it no longer corrupts your login and password file. To manually trigger an update to AVG:

Double-click the AVG icon on your desktop to open the application.
Click the Refresh icon next to Virus definition in the bottom-right corner of the main AVG Antivirus screen.
Wait while AVG checks for virus definition updates.
When the update is complete, you see Virus definitions are up to date.
If you are asked to restart your PC, click Restart Now to reboot immediately.

Firefox logins and passwords can now be recovered with the following steps:

Open the Firefox web browser.
Click the menu button , click Help and select Troubleshooting Information.
Click on the "Open Folder" button near the top of the page that opens; this opens the profile folder.
Close Firefox.
Check if you see a file called logins.json is in your profile folder.
- If you do rename it to logins.json.oldempty
Check if you see a file called logins.json.corrupt with a June 2019 date in your profile folder.
- If you do, right-click, copy the file and rename it to logins.json.
Start Firefox. Passwords should be available, and you should be able to sync without signing in again.

Fix passwords disappearing due to AVG security software