The mime types provided by /usr/share/mime/packages/chemical-mime-data.xml makes update-mime-database to emit error messages like "Unknown media type in type 'chemical/x-turbomole-grad'". I don't know if it is the mime type to be wrong or update-mime-info to be too picky, though. Reproducible: Always Packages: sci-chemistry/chemical-mime-data-0.1.94-r3 x11-misc/shared-mime-info-1.6
Just leave them. THese warnings have been there for ever. No idea where they came from but they do not harm.
Interesting approach. The issue is there, no idea about it but it does no harm, so close it. I'm not really sure how you can say that there is no harm when you, admittedly, have no idea about it. I understand that you may have no time or will to look at it, but closing the ticket is probably the worst thing to do. And "works for me" is a bogus claim, as it *does not* works for you. Maybe leaving it open will allow with someone with more clues about the issue to solve it, what do you think?
I've found the cause of this. The package sci-chemistry/chemical-mime-data adds a file usr/share/mime/packages/chemical-mime-data.xml that has all these unknown mime-types in. The utility update-mime-database which is part of the package x11-misc/shared-mime-info has a hard coded array of media_types[]: /* This is the list of directories to scan when finding old type files to * delete. It is also used to warn about invalid MIME types. */ const char *media_types[] = { "text", "application", "image", "audio", "inode", "video", "message", "model", "multipart", "x-content", "x-epoc", "x-scheme-handler", }; The function get_type() in update-mime-database.c compares the mime type to this array and since "chemical" is not in this list it prints out a warning. It seems like a harmless warning, but it is a pity there is not a way to suppress it. Solution include removing the warning from update-mime-database, add "chemical" to the media_types array, or only display these message if -V (verbose) added to update-mime-database command.
Created attachment 452041 [details, diff] chemical type patch
I tried to add "chemical" to the list of directories and indeed the messages disappears, as suggested by Steven Green. If someone is bothered by this message as I am, just create /etc/portage/patches/x11-misc/shared-mime-info-1.7/ and put in it the attached patch...