Having quite a few problems with TeamViewer on macOS Monterey 12.6.5 (as my Mac cannot be updated to later versions of macOS. This is the latest available update for my Mac).
I've found that when TeamViewer is configured to start with macOS, it becomes impossible to quit the application, which then prevents the Mac from rebooting. Trying to force-quit TeamViewer doesn't work well either, with the TeamViewer app immediately restarting. In trying to resolve these problems, I reinstalled TeamViewer. I even used the uninstall option from the Advanced Settings menu inside Preferences and included the option to delete configuration data. After reinstalling from scratch, I still see the same behaviour. Reinstalling hasn't fixed any of these issues.
The version I downloaded from the TeamViewer website was 15.41.7. Immediately on starting, the app says that an update is available to 15.41.8. While the app is configured to start with macOS, the update will download but the next step of beginning to extract the update never starts. It just hangs on the "downloading update" window, even though the update has completely downloaded. If I change the configuration back so that TeamViewer does not start with the system, the update process at least asks for my macOS user password and then begins, but every time it refuses to proceed with the error:
"Update Error! The update is improperly signed and could not be validated. Please try again later or contact the app developer."
Has anybody seen this and resolved it?