I just updated to Mac OS X 10.6 Snow Leopard. My hard disk was still partitioned with the old Apple partition scheme – but Snow Leopard needs the new GUI partition scheme. So I had to do more as usual to do the update: First a complete backup of my hard disk (you absolutely should do this every time you update your system), then I had to erase and repartition the HD with the GUI partition scheme. After that I was able to install Snow Leopard and transfer my user data from the backup, the programs, etc. with the Migration-Assistant.

Using Snow Leopard feels great and you immediately recognize the speed. Looks like all of the Apple engineers work “under the hood” was worth it! You should not expect fundamental changes within the user interface or other totally new features – the core of Snow Leopard are speed, detail improvements and technology upgrades.

But what’s about the compatibility to non-Apple-hardware products? Sadly, printing on my OKI laser printer does not work with the Leopard-compatible driver for the Oki MFP C5540. By using the preinstalled generic PS-printer-driver from Apple you are able to print on the OKI printer – you even an control the duplex unit. But you are not able to control all the specific printer settings like print quality, grayscale instead of color printing or specifying the installed memory on the printer. But, who knows how long Oki will need to update their printer drivers for Snow Leopard? That’s why I started debugging myself. So, here is the solution for all the fellow sufferers who also own an OKI printer … and as always: no guarantee and on your own risk:

Problem: After updating from Mac OS X 10.5 Leopard to OSX 10.6 Snow Leopard the installed printer driver for the OKI-postscript driver does not work anymore. Here it’s an OKI MFP C5540 … but it should also work with other models, like the OKI C5450 or C8800. The printer diver was installed under Leopard and worked quite well. After finishing the update to 10.6 you are able to send a print job to the printer, but an error message shows up in the print queue.

UPDATE: You’ll find an updated diagnosis & solution in the NEW BLOGPOST!

Diagnosis: There is a bug in the printer driver … the bug had no effect under Leopard (maybe because of the Apple partition scheme). When OKI coded the printer driver, they disregarded case sensitivity in their path names … former systems did not care about case sensitivity – but Snow Leopard does!
Solution: The fast work around is to use the generic PostScript-printer driver – but there you don’t have the possibility to set the OKI-specific printer settings. That doesn’t make me happy 😉 To get back the whole functionality of the Leopard OKI-printer driver there is only one way: Hands on coding and debug 😉 Fortunately fixing the bug is no rocket science – you only need a text editor like TextEdit or TextMate and you don’t be scared program code:

  1. Search for your Oki-printer driver PPD-file in the Finder … you should find it under
    Macintosh HD/Library/Printers/PPDs/Contents/Resources/

    mine is called “Oki C5540.ppd”.

  2. Before you go on make a backup of this file … this way you always can come back to the original state. 😉
  3. Open the PPD-file with the text editor and search for the following line:
    *cupsFilter: "application/vnd.cups-postscript 0 /Library/Printers/OKIDATA/Filters/OKfilterA"
  4. Then search for the file “OKfilterA” … I found mine under the following:
    Macintosh HD/Library/Printers/Okidata/filters/
  5. Now, adjust the path in the PPD-file … the line in my corrected PPD-file looks like this:
    *cupsFilter: "application/vnd.cups-postscript 0 /Library/Printers/Okidata/filters/OKfilterA"
  6. Now, you only have to save the file and restart your Mac … now it should work 😉

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