Thunderbird 68.x: Update loop due to Phantom Updates

[German]The email client Thunderbird causes in version 68.x unexpected issues for some of its users. The program reports an update, which does not really exist. The mail client goes into an update loop and tries to update itself again and again. The reason seems to be Kaspersky antivirus software.

German blog reader Ralf drew my attention to this behavior (thanks for that). Ralf writes about it.

Since TB 68.x there have been repeated problems with some users that a "non-existent" update is displayed.

The problem is that the Thunderbird version 68.x reports that an update is pending. If the user then tries to install this update, but there is no newer update. Although the user let Thunderbird install the reported, update, a new message about a pending update occurs. Pretty stupid.

Posts in the Mozilla Forum

Users have raised the issue in various forum posts. Ralf then referred in a mail to this forum post.

How many times do I have to download and install Thunderbird? I still get an alert to update

I've downloaded and installed this new version of Thunderbird at least once, twice if I did it correctly the first time. I still get an alert stating that Thunderbird can't update to the latest version.

A second user confirms this. Also in this forum post this problem is described. Here is a picture posted by one of the affected users.

(Source:Mozilla-Forum, Thunderbird Update Loop)

The user posted at the end of October 2019 the Thunderbird version display dialog shown above, which reports version 68.2.0. Nevertheless, the update notification appears in the background with a request to download the 'latest Thunderbird' – which makes no sense. There is version 68.2.1, but it doesn't solve the problem – because the root cause for this issues lies somewhere else.

Blame Kaspersky

Soon users in the Mozilla forums expressed suspicion that an installed Kaspersky product was involved in this update loop. In n this Mozilla forum post, an affected user writes that he has deactivated his antivirus software and then carried out the update. This solved the problem for him. However, another user writes that it did not help him.

Later it became clear, it is the antivirus component from Kaspersky that probably interferes with the Thunderbird update process. In this Mozilla forum post someone suggests a workaround.

Here's a workaround for Kaspersky Internet Security (KIS): Exclude aus.thunderbird.net.

This person propose to remove the URL of the domain to download the Thunderbird (aus =  automatic update search) from Kaspersky's monitoring. Here are the steps:

KIS > Settings > Protection > Mail Anti-Virus and Anti-Spam are enabled at their defaults settings.

KIS > Settings > Additional > Network > Monitor all network ports is selected.

KIS > Settings > Additional > Network > Always scan encrypted connections is selected.

KIS > Settings > Additional > Network > Manage Exclusions > Add > aus.thunderbird.net > Add.

Within the thread, this person also specifies how to determine the download domain for updates from the Thunderbird configuration.

Description in the BugZilla Bug Tracker

Ralf then referenced in his mail to the bug report "Thunderbird can't update to the latest version. … Download a fresh copy…", where the problem is summarized with references to various posts in forums. Ralf wrote:

In Bugzilla it is said that several users named Kaspersky as the reason for this unsuccessful update update notification. Obviously it is the virus protection, here e.g. Kaspersky IS 2019 / KIS2020.

Ralf writes in his mail that other antivirus programs could also cause this effect. Do you know if an update loop occurs in the Thunderbird? Thanks to Ralf for the information.