Thunderbird 38.4.0 has not yet been released. Reviewing the notes from the status meeting on November 3rd, the release was planned for around November 5th. This delay is not unusual and likely we will be seeing the Thunderbird 38.4.0 release during this coming week. While going through the meeting notes did notice bug 1211160 which had to do with ‘some’ users who updated to Thunderbird 38.3 with Lightning 4.0.3 enabled lost use of the buttons in Thunderbird. Users reported that rolling back to Thunderbird 38.2.0 resolved the issue. Other uses reported success by disabling Lightning 4.0.3 prior to updating to the…

The “Hibernation Bugs‘ which affected Thunderbird’s ability to fetch new mail as well as Lightning after coming out of hibernation (or sleep) have been fixed and will be included in the Thunderbird 38.3.0 release on Tuesday, September 22nd.