The pausing of the printer queue can be caused by an inability to connect using the selected protocol or find the designated port on the printer. Sometimes you can fix this by deleting the printer and reinstalling.
Another thing that can help is the Reset Printing System. With System Preferences > Print & Fax open, hold the Control key down and click inside the printer list. Reset printing system should appear and when you select it all printers will be deleted from the printer list, meaning that you will need to create the printer queue again (should be no need to install the driver again).
If reinstalling the printer is no help, then you can open the printer queue and check the log. In the Print & Fax section, select the printer in the list and select Open Print Queue. WIth the new window open, select Printer in the menu bar and then Log & History. This will display the cups error log which can give clues as to why the printer queue is pausing. The E in the left column indicates the error and the data about that will pertain to the print job that ended in error.
After OS X 10.6.8 was released last Thursday, a number of people found that their printers were no longer printing, where the system would show the printers in a paused state and no print jobs would work. This problem seems to behave differently for different setups, but overall appears to be a bug with how CUPS handles its backend processes.
The back end in the CUPS system is the interface for various transmission protocols for both networking and direct connections to the printer. While some people may benefit from the aforementioned fixes of running general maintenance, resetting the print system, and reapplying the latest “Combo” updater, it appears a true workaround until Apple addresses the problem is to replace the transmission protocol file you are using with the one from OS X 10.6.7.
In order to do this, you will need your Time Machine backups or another Mac running OS X 10.6.7 and then run the following procedure:
- In the Finder’s “Go” menu select “Go to Folder”
- Type “/usr/libexec/cups/backend” in the field and press enter to go to the hidden “backend” folder.
- Open the “Console” utility to see what backend file is being used. When your print job fails you should see a message similar to the following (in this case it is the “lpd” backend):
- In the Finder with the “backend” folder window open, invoke Time Machine and then go back to before you updated OS X (sometime on June 23 should work) and restore the file, replacing the one in the “backend” folder. If you do not have Time Machine, you can copy the file from the same location on another Mac.
- Close the Finder window and then perform a Permissions Fix on the boot drive using Disk Utility.
- Go to the “Print & Fax” system preferences, right-click the printer list and reset the print system, and then set up your printers again.