David26
Please put triple backticks before and after terminal output. I have edited your post to have them.
I maintain the hplip software for Solus. It's not necessary to use its specific commands to install printers. You can install hplip and then remove or add printers in the system settings. The only thing it's sometimes necessary to do with the hplip commands specifically is run hp-plugin, which you've already done.
From the screenshot in your original post, it looks like the printer is stopped, possibly due to an error, and that there are jobs in the queue. The text says to restart the printer after resolving the problem (whatever it thinks the problem is).
What I suggest you try now is:
1 - Remove all instances of the HP printer (I see 2 in the screenshot) and the CUPS-BRF-Printer. If you don't have a MFC-5860CN, remove that too.
2 - Re-add the printer through the normal system printer settings
3 - Make sure there are no jobs in the queue and no errors shown
4 - Try to print a test page
If you see errors again you might try restarting this service:
systemctl restart cups-browsed.service
As a side note, we are working on updating CUPS, hopefully that will help with weird errors like this.
I also found this upstream bug that looks related, just including it for information's sake
Let us know what happens.
