I have no POP account all are IMAP Accounts. It is not possible here to select “Default Folders”
Ok if its an IMAP account sounds like something has gone wrong either with “your account”, or “the database” or “possibly the installation”
So if you have been making regular eM Client backups, then try restoring a recent dated backup when you know it was working ok without that error via “Menu / File / Restore” and any new messages etc will update when eM Client next reconnects.
If you don’t have any recent eM Client backups then go to “Menu / Accounts” and try removing and re-adding your IMAP account again and see if that fixes it. For a Gmail account “make sure you select the calendar” when you get asked to allow eM Client access to your Google account “near the end of the automatic account wizard”..
If removing and re-adding your account still doesn’t fix it, then “try creating a new clean database” to test. To create a new database, “close eM Client” and then “go to the following hidden database folder” below and “rename it” to eg: eM Client-Current . Then reopen eM Client and setup as new and see if that fixes it.
(Hidden database folder Windows)
C:\Users%username%\AppData\Roaming\eM Client
(Hidden database folder Mac)
/Users/User Name/Library/Application Support/eM Client
If a new database still doesn’t fix it, you might need to uninstall and reinstall eM Client. So if you originally installed eM Client from the website, you can download all the latest versions for whatever you originally installed via the release history page
Apart from that if still the same error and you have a current active paid Pro, Personal or Business version, then go to the VIP support page and login and lodge a support ticket. If you have run out of your support time you can get another 12months ext via this link.