Cannot restore from backup

I am trying to restore my account data from a backup, which was taken a day ago.
The app always thorws this error message:

eM Client (6.0.24928.0)
Windows: Microsoft Windows NT 6.1.7601 Service Pack 1, Framework: 4.0.30319.34209
The following error has occurred:
System.TypeInitializationException: The type initializer for ‘MailClient.Storage.Application.Folder’ threw an exception. —> System.Data.SQLite.SQLiteException: SQL logic error or missing database
no such table: folders.Folders

I need your help.
Have already sent the above log content but have not received an answer yet

Hello Wolfram,
seems like your database files are corrupted and eM Client can’t load the data from it.
Delete your current database files from C:\Users%windows user account%\AppData\Roaming\eM Client folder.
Start eM Client with a clean database and either load your data from a backup using File>Restore option or set up your accounts anew.