thank you, Alan,
your solution worked!
It was a file, really: PANTONE+ Solid Uncoated-V2.clr (attached here, data: 2016).
If I remove this Emacs generate its file and no error or warning happens.
If think I could remove the files, as I’ve also another file, PANTONE+ Solid Uncoated-V3.clr (2019) that should be the replacement…

Now Emacs doesn’t generate the warning.

Thanks again,
Salvo