It seems these tracing messages are outputted by the kde-open5 utility. I do not think we should hide at xdg-utils level any messages from underlying tools. However, you may redirect unneeded output on your own.
$ xdg-open readme.pdf >/dev/null ** Changed in: xdg-utils (Ubuntu) Status: New => Opinion -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/849413 Title: xdg-open spitting out debug messages on start To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xdg-utils/+bug/849413/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs