If the queue is created by:

$ lpadmin -p test -v ipp://192.168.5.5/ipp/print -m everywhere -E

and PPD generation fails - f.e. due invalid attributes in printer's IPP response - cupsd leaves the print queue present as raw instead of deleting it.

The fix is to make the failed queue temporary and let the main process remove it - https://github.com/OpenPrinting/cups/commit/2e3f15832 .