How to remove unknown external storage backend (NC25)

Hi there,

in my quest to solve steadily growing warnings given off by NC, I wanted to check if server-side encryption could be disabled

While running command ./occ encryption:scan:legacy-format, I got the following error:

In FailedStorage.php line 209:
Unknown storage backend “files_external_dropbox”
In FailedStorage.php line 209
Unknown storage backend “files_external_dropbox”
In InvalidBackend.php line 64:
Unknown storage backend “files_external_dropbox”

I’m pretty sure the backend was installed along with Dropbox app in the past (my shared hosting is rather small, so I’d add any available external storage).

The problem is, from my limited understanding, the backend wasn’t removed when I removed the Dropbox app.

How do I get rid of this ?