Yesterday I was able to generate a file type not detected error
Being lazy instead of creating a local.convs file, I deleted mime.convs and swapped in a new mime.convs with filters to foomatic-rip
using a foo-rip PPD failed, I then went back to hplip PPD without reversing my mime file and got the error.
So it looks like file type error points to a bad syntax mime or local (.convs) files or
-- missing attribute in one of them
so if you try to print a pdf and you have no mention of what filter to use with pdf files you are likely to see that error
"file type not detected"