There is already a sync from the server to this local folder

I removed my account from the nextcloud desktop sync client and added it back. But when I try to add the folders to sync, it says “Warning: There is already a sync from the server to this local folder. Please pick another local folder!” And the next button is disabled.

The folder path is /home/***/Nextcloud

It seams to want to create a new folder named “Nextcloud2”. But I don’t want that. How do I set it to the original “Nextcloud” folder?

I deleted from my local folder files with the following extension, and the next day the error went away.

* .sync_*