I ended up making sure all data the map document was using was located in a file geodatabase (in a subfolder for organizational purposes) in a registered folder on the hosting server. I did end up manually grabbing the file geodatabase out of the original map package folder and placing it in the registered folder.
There may be a more straightforward way to handle this issue, but it seemed to work fine for me. Best of luck!
Hello, same problem here.
Putting the data to a registered folder didn't help.
Neither restart of the publishing service or the whole server.
What does this error really means?