"There was an error adding the media path"

[Cognicom]

Fileshare is set to "Everyone" and full rights.  Running windows 10.

Microsoft's interpretation of "everyone" hasn't always coincided with logic, especially since Windows 10 - and based on many reported problems over the years back in Reddit (and prior) days, most problems are associated with file permissions.

Having said that, it's unlikely that it's a permission issue with your media folder - if it was, you wouldn't be able to play/access existing (already in the database) media. More likely, it's a permission issue with your metadata folder.

AFAIK, the default paths for cache and metadata on Windows are;
C:\ProgramData\Jellyfin\Server\cache
C:\ProgramData\Jellyfin\Server\metadata
- but you can confirm their precise location by going to Dashboard -> General and looking at the paths specified there.

Then as a test, go and set "wide open" (i.e., "classic Microsoft") permissions on the folders to see if it's a permission issue here;
- Add "Guest" or "Guests" to the list of permissions,
- Assign "full control" to the added account, and make sure the properties are propagated to all child paths and files.

... Then check to see if Jellyfin can successfully add new media to its database - if so, it is a permission issue, and you can then go about properly rectifying it (which would involve firstly removing that "Guest" entry in order to regain safety, then adding whichever user the Jellyfin process runs under to the permissions list).

Another thing to check (though it probably won't be the cause, as Windows would surely have screamed a long time ago if it was) is how much free space you have on the drive housing the metadata.