We had a problem when our main directory suddenly disappeared.
We searched everywhere, but it was nowhere to be found.
We thought someone had deleted the entire folder, but in fact no one had deleted it, because the space on our server had remained the same.
Someone had accidentally moved the root folder to one of its subfolders, and suddenly the root folder and its subfolders were no longer accessible.
Moving a folder within itself should generally not be allowed.
We managed to fix the problem by changing its parent connection (fs_dir) to the right folder directly in the database.
I logged into the server via SSH and ran the following commands.
select * from egw_sqlfs where fs_name = "our folder";
update egw_sqlfs set fs_dir = "rootID" where fs_name = "our folder";