Thunderbird version 68.0 is only offered as direct download from thunderbird.net and not as upgrade from Thunderbird version 60 or earlier. A future version 68.1 will provide updates from earlier versions. If you have installed Lightning, Thunderbird's calendar add-on, it will automatically be updated to match the new version of Thunderbird. Refer to this Calendar troubleshooting article in case of problems.

System Requirements: • Window: Windows 7, Windows Server 2008 R2 or later • Mac: Mac OS X 10.9 or later • Linux: GTK+ 3.4 or higher. Details here.