File could not be written

I am using MP3Tag on my Bluesound Vault2 for my Classical cd collection. Trying to add the cover I get a pop-up screen saying that the file could not be written. What could be the solution? I have MP3Tag version v2.94

Here is a thread that deals with the problem:

One of the following is often the cause:

  • insufficient access rights
  • insufficient ownership
  • simultaneous access blocks files
  • corrupt files.