Some TXXX tags are written in lowercase

I found out that if you write some of the TXXX tags by clicking on their field inside their column (e.g. mapped as %artists%), Mp3Tag writes it as TXXX:artists instead of TXXX:ARTISTS, which causes problems with other taggers such as MusicBrainz Picard. However if you tag your files by clicking on "Extended Tags...", the tag is being written correctly as TXXX:ARTISTS. I tested %artists%, %albumartists% and %album_artists% so far and all of them are affected, so it's possible that it's a bug with all TXXX tags. I'm using ID3v2.4 UTF-8 setting.

Thank you so much for the fix!

Here is s a thread on how to modify the case of a field name:


Is there a known standard how to write such tags?
Is this "all uppercase" only valid for TXXX tags or for all ID3 tags?

What about other tag types like APE?

Actually, if a program can cope with user-defined fields (only very few can), then it should not bother about the case.
On the other hand: MP3tag allows you to adapt so many settings so that the target player is satisfied, you probably have to adapt your files so that the other program can deal with it.

Just for the record:
There is an open issue at MusicBrainz for their Picard related to this bug report:
"Read & write the ID3 tag fields in all caps":

I'm not sure what the solution will be.

I know I can modify fields myself, but shouldn't this be fixed as well? What I mean is that if I write ARTIST in Extended Tags, it gets saved into TPE1 tag. If I write it into the %artist% column, it gets saved into TPE1 tag (not tpe1). So why if I write ARTISTS in Extended Tags, it gets saved into TXXX:ARTISTS tag but if I write it into %artists% column, it gets saved as TXXX:artists and not TXXX:ARTISTS?

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I opened that issue and because I was told that musicbrainz fields won't ever be capitalized, the remaining ones that I know of are TXXX:Writer and TXXX:albumartists. As for why it was decided that they should be all caps, I don't know.

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You probably need to be careful with the column specification then and use %ARTISTS% instead of %artists%.

I don't consider this a to be a bug in Mp3tag, so this topic has a new home under #support


I think because this is a user-defined field for which the user has full control.
The fields that find an equivalent in the id3 standard are mapped, user-defined fields cannot be mapped to anything but themselves.

Thank you for your feedback! I will use %ARTISTS% (as well as any other TXXX tags) from now on.

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