Tagging was working fine until I updated yesterday, now I get these errors. Anybody else having this problem?
See, if this helps:
Hey thanks, ohrenkino, but that and "delete app.mp3tag.Mp3tag SecurityScopedBookmarks" has not helped. Nothing that I am aware of has changed except for updating the sw...?
The trick is not to open a single file but the top folder after you have deleted the bookmarks.
That's what I've been doing. The error is coming when I am trying to send the files from one folder to another.
Can you try opening the folder that also includes the target folder?
The issue you're experiencing is due to Mp3tag being a sandboxed application. Sandboxed applications require explicit access to files and folders provided by the user via
- an open panel, e.g., with ⌘O
- Drag & Drop
- Services
Mp3tag tries to remember once the permission is given via a "secure bookmark" (the list of them stored at SecurityScopedBookmarks as you already found out). This allows for editing the same files without subsequent requests for permission.
If you drag&drop or open individual files, Mp3tag only gets permission to edit those files. Renaming also requires permission to the enclosing folder. I believe this is what you're observing.
The good thing is, that those secure bookmarks apply to all included files and folders or a folder for which the permission is given. So if you choose a more general folder (e.g., your home directory at ⇧⌘H in the open panel or the external volume in your case), you can prevent future prompts for any of the containing files and folders. You can also cancel the reading process if it takes longer than acceptable — Mp3tag will store the bookmark no matter what.
Hi - thanks for all the help 
I deleted the app and reinstalled and all is fine now.
Cheers!