I can't add AAC file to iTunes Library: drag doesn't work. Couple of weeks ago this worked OK.

Yes...! It works. itunes app accepts .m4a file and shows .aac file type in 'song info'.

This is because both .aac & .m4a are extensions of AAC codec.
Its that SIMPLE.

Find the file in Windows, right-click it, and choose Open With > iTunes.

If the file is compatible, it will be added to the library and start playing.

If "nothing" happens, there is a problem with the file.

😀 nice for finding the problem for windows but we have this problem on Mac's.

I tried everything and I still can't import the acc file's

infinity_atom wrote:

😀 nice for finding the problem for windows but we have this problem on Mac's.

I tried everything and I still can't import the acc file's

Drag the audio file into the Automatically Add to iTunes folder, which is found in your iTunes Media folder.

If the file is compatible, it will be whisked away to your library. If it is not, it will show up in the Not Added folder.

Yep ed2345, as I said I tried everything and still doesn't work but I found something else

.m4a extension is something like .aac but works added

I didn't understand very good but it seems to be the same kind

When I add an .m4a it says that is an AAC file

In conclusion try using .m4a instead

(edit -- removed)