Based off your screenshot, you got an older version of CB2021. Download/install the latest CB2021 installer (v20.0.2.1884) from your online account here: https://www.comicbase.com/mycb/Registrations.aspx
See if you're able to launch the software after installation with no trouble.
If the problem still happens, check if you have recently dated backup of your database you can load instead that's free of the problem and use it going forward. By default, backups are stored in Documents/Human Computing/ComicBase Databases folder.
If you still have no luck, please contact our support team at support@comicbase.com OR 408-266-6883