The database of security certificates changed from cert8.db to cert9.db. The database of keys required for encryption/decryption of passwords, etc. The security database was changed in Ver.52 > Ver.60. This is because profile specification changes along the way may not work. It is important that the upgrade be done in stages and in sequence. Then go up three levels (Roaming folder) and copy the entire Thunderbird folder and paste it somewhere else. In Thunderbird, open Help > Troubleshooting Information and clickĪpplication Basic Information > Profile Folder: “Open Folder” will open the profile folder in use. However, if you install and start Thunderbird 91 out of the blue, trouble is expected to occur because the version is too open. In older versions, the authentication method is “Normal Password Authentication” and the application password must be issued on the Google Account side. Google’s 2-step authentication, “OAuth2” supported by older versions of Thunderbird, is not compatible with the current Google. In view of the latest security measures, I strongly recommend that you migrate to the latest version of Thunderbird 91. In short, I believe that Gmail will no longer be available in versions older than Thunderbird 68. Less secure apps & your Google Account – Google Account Help Google will end support for insecure apps (e.g., older versions of Thunderbird) on May 30 of this year. Is that correct? Or will all Thunderbird users have to upgrade to version 91 in order to make Gmail work?

Just as a point of clarification, older thunderbird versions eg from 36 to 78, already have OAuth 2.0 so they won’t need to do anything.

Thunderbird gmail