I recently switched to Thunderbird and at first it worked. However, now I'm always shown an error message like

The current operation on 'Inbox' did not succeed. The mail server for account [email protected] responded: System Error (Failure).

when clicking on my inbox folder of that account. The same also happens when I click on the "Important" folder of that account or on "All Mail". It does, however, not happen when clicking on "Starred", "Sent Mail", or "Drafts".

I of course googled this problem and read that this happens when IMAP is disabled. However, I didn't touch the settings of my email account before this problem randomly occurred. Disabling and re-enabling IMAP did not help either.

IMAP also does not seem to be disabled as the computer I'm writing this on still downloaded messages from various folders a few minutes ago and a different one is still downloading messages in "Sent Mail" and important. The installation of Thunderbird on the other computer shows me the same notifications.

Neither of these installations show my latest messages in my inbox of that account.

However, both installations also are connected to a different Google Account that still works perfectly.

How can this problem be resolved?

I recently switched to Thunderbird and at first it worked. However, now I'm always shown an error message like

The current operation on 'Inbox' did not succeed. The mail server for account [email protected] responded: System Error (Failure).

when clicking on my inbox folder of that account. The same also happens when I click on the "Important" folder of that account or on "All Mail". It does, however, not happen when clicking on "Starred", "Sent Mail", or "Drafts".

I of course googled this problem and read that this happens when IMAP is disabled. However, I didn't touch the settings of my email account before this problem randomly occurred. Disabling and re-enabling IMAP did not help either.

IMAP also does not seem to be disabled as the computer I'm writing this on still downloaded messages from various folders a few minutes ago and a different one is still downloading messages in "Sent Mail" and "Important". The installation of Thunderbird on the other computer shows me the same notifications.

Neither of these installations show my latest messages in my inbox of that account.

However, both installations also are connected to a different Google Account that still works perfectly.

How can this problem be resolved?