Was using version 5.0.19406.0 without any problems and the auto-updater alerted me that version 6 was available, so I agreed to update it.
After the download & install, every time you try to run eM Client, it crashes on startup, showing the attached error (see image). When you click on “continue”, it cycles through to check the database and for inconsistent data (all checks out), then attempts to restart, but gets back to the same crash/error screen again.
Restarting the computer does not help. The error detail log is available (very long text file) if it may help.
Luckily, I always make a copy of the original eMClient folder before an update, so I have now had to revert back to version 5 until this is solved.