[rents1977]

As per title.

I have an Ubuntu server, I host the files via NFS and the library via MySQL to some Firesticks, Kubuntu laptops and an Xbox One.
It worked flawlessly until I upgraded from Leia to Matrix. The Artist Information folder (viewable in files, and read/writeable, tested by creating a new folder) is throwing up an access error message, and as such the Artist View is no longer useable (however artist artwork does show up when playing).

After 3 days trying to resolve it I have abandoned it and gone back to local libraries, which work flawlessly.

I understand from various posts around the forum MySQL is basically unsupportable from a dev's point of view because it can't be replicated on another machine and the debug process is nigh on impossible. I'm wondering though if somehow the location string "nfs://xxx.xxx.xxx.xxx/mnt/HDD1/ArtistInfo/" is breaking an SQL query, but I don't know where to start trying to investigate.

[bossanova808]

Where are you actually seeing the error?

I do basically the same thing (although my NFS is using Hanewin NFS on Windows), and use MySQL with Matrix, and am not seeing this issue.  I know that doesn't help much, but is just for extra info.

[Klojum]

The Artist Information folder (viewable in files, and read/writeable, tested by creating a new folder) is throwing up an access error message, and as such the Artist View is no longer useable (however artist artwork does show up when playing).

An "an access error message" is still pretty vague. We will need more detailed info there.

After 3 days trying to resolve it I have abandoned it and gone back to local libraries, which work flawlessly.

Believe it or not, the local libraries also work with SQL, so there may be something specific about your MySQL/MariaDB(?) setup. Which is a bit odd, as I myself have used NFS & Ubuntu/MySQL since the starting XBMC days about 11 years ago, and now use Ubuntu Server (18.04) with MySQL 5.7.35. And although I do not listen to the music section in Kodi very often, I have yet to encounter 'an access error message'. Do you get this access error message on all of your Kodi client devices? Then it would be indeed a server problem.

I understand from various posts around the forum MySQL is basically unsupportable from a dev's point of view because it can't be replicated on another machine and the debug process is nigh on impossible. I'm wondering though if somehow the location string "nfs://xxx.xxx.xxx.xxx/mnt/HDD1/ArtistInfo/" is breaking an SQL query, but I don't know where to start trying to investigate.

MySQL/MariaDB itself is not a Team Kodi product, so the real technical side should be handled by their respective developers/maintainers. However, some things are of course intertwined, so we'll need some more information from you first, such as Kodi's debug-enabled debug log (wiki) as well as MySQL's own log file to see where the culprit may come from.

[DaveBlake]

I don't think this is related to MySQL in any way unless you can provide a debug log file with a SQL error in it. Users get a fair amount of support for set-ups using MySQL/MariaDB, and a number of team members and expert users have Kodi based around it, but it can be very difficult to support users that are less technically minded.

Getting "access error messages" is more likely related to where the common Artist Information Folder is and if that lies on a path that has been added as a source. Matrix as added security and so can only access locations that you have added as music/video/picture sources, and the AIF may not be on one of those.

On the other hand it could be about differences in the way that  NFS is mounted for Matrix compared to Leia (and I don't know if there are any in the many OS you are using).

Best way forwards is to turn on debug, reproduce the access error messages and paste a log file link here.