CUPS generates “Internal server error” when visiting administration page

It seems that Mac OS Lion server (10.7.0) may have been released with a broken CUPS configuration. Visiting http://localhost:631/admin would generate an “Internal server error”, this seems to be addressed in newer builds (my Macbook Pro which was install from a 10.7.2 image does not exhibit the problem yet a customers server which came bundled with 10.7.0 (upgraded to 10.7.1 > 10.7.2) does).
To resolve the issue sudo cupsctl --debug-logging
Then switch off the debug logging with sudo cupsctl --no-debug-logging

I suspect the problem is due to a missing directory because comparing the default, previous & current revisions of the /etc/cups/cupsd.conf did not show anything that could cause problems.
I’d also go far as to say that you don’t need to turn on debug logging in-order to resolve this issue, it can be any of the options that can be set via cupsctl as it checks the configuration of the system, this is just a theory as I was unable to dig further because I was on a production system. Resetting the printing system did not solve the issue when attempted previously.

25 Replies to “CUPS generates “Internal server error” when visiting administration page”

  1. Worked for me too. Mac OS X 10.7.3 Server on a Mac Mini Server.

    I would love to know what actually happened to make this work. As you already saw, cupsd.conf didn’t change.

  2. I tried

    sudo cupsctl –user-cancel-any

    and that made things work. So the OP’s guess that this doesn’t have anything to do with logging seems to be correct.

  3. Thanks a lot for this tip. Found you using Google based on CUPS error, applied the cupsctl logging trick, and cups admin services were available again.

    MacBook Pro, 10.7.3. (originally came with 10.7.0).

  4. Thank you for sharing this information. I wasn’t able to set-up my shared Lion printer on Win 7 because of the broken default config but once I tried your suggestion it proceeded as I expected.

    I just hope it doesn’t reset itself when the machine reboots.

  5. Man! Apple is turning into Microsoft and Microsoft is turning into the new Apple! Heck, they’re even manufacturing our own tablets too! It’s about time Apple had some competition!!!

    Thank you very much for writing this succinct, effective article!. Turning off the debugging immediately solve the problem. Considering that this is the middle of 2012 and Lion is at 10.7.4 you would think this would’ve been solved by now by Ineptple.

    I used to like Apple (Ineptple) but then Steve jobs died and they turned into just any other money grubbing, spirit crushing Corporation. Time to take them apart!

  6. It worked perfectly. Thanks a lot !

    And NO thanks to Apple, one more time 🙁

  7. Giving the command

    sudo cupsctl –user-cancel-any

    allowed access to many of the CUPS information and maintenance pages but (for example) when I tried to access items on the Administration drop-down menu of a printer in the Printers tab it initially denied access but later did allow access (to change the default options to switch to A4 as default not US Letter page).

    I’m running Mac OS X 10.7.4

  8. Hey. Worked for me: 10.8.2 Mac Mini (Mid 2011) as upgrade from 10.8.0 base install.

    The oddity with mine is that it worked, then started failing (ie reload yesterday’s help pages, and now they fail), and your trick of hats-on-hats-off with the debug flag shook things up to be working again. Odd.


  9. I’ve had the dreaded Internal Service Error occur sporadically from week to week. When it happens, nobody can print to our Lion print server. Until now, I’ve been using the following to restart the service on the server:

    sudo launchctl unload /System/Library/LaunchDaemons/org.cups.cupsd.plist
    sudo launchctl load /System/Library/LaunchDaemons/org.cups.cupsd.plist

    Unfortunately, the error always comes back. Here’s hoping your solution solves it for good.

    As an administrator, I’ve been quite disappointed in Apple lately, and I’m looking for options to switch more and more of my services over to Linux and Windows Server.

  10. It worked for me too!

    10.7.4 on macbook air. Cups always said ‘internal server error’ until I tried your commands.

  11. Yes, it’s the way to fix the problem. 10.8.4 with Software update patches through 27JUN13;

  12. 1) File a bug report with Apple.
    2) File a feature request with Apple to bring back GUI Print Server support in OS X Server app.

  13. After upgrading to OSX 10.9 (Mavericks) CUPS was giving me internal server errors. This fixed it!

  14. You may also run ‘sudo cupsctl WebInterface=yes’ to restart the web interface.

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