With the release of Firefox 67.0.2, some users began noticing that the browser had stopped automatically filling in their saved logins. When they tried to access their logins using the Firefox password manager, they noticed that the list was empty. Users checked to see if this file existed, they found that it was renamed to logins.corrupt as shown below. Avast has created a fix to include Mozilla’s new certificate in their program. Users need to wait for VPS definition version 19061402 to be downloaded by their AVG software.
Source: https://www.bleepingcomputer.com/news/security/avg-password-protection-blocked-firefoxs-access-to-saved-passwords/