@Impact Imaging: Your hint for the mountain lion driver helped for CP780.
@ Christian: Great job!
First I tried the package from Christian posted above and chose the driver CP800 as some mentioned in this post. It failed on a retina MBP mid 2014 with all recent Yosemite updates. Neither printer switch on/off nor system restart worked.
I downloaded the lion driver from Canon and modified the settings from distribution.dist and run the package.
This was a very well known method to install the driver on Mavericks. See link for details how to do it. Sorry, it is in German, but you will find this also in EN somewhere.
http://schmid.tv/2013/11/basteltipp-canon-selphy-cp780790800810900-unter-macos-x -10-8-und-10-9-mavericks-nutzen/
I removed the CP780 from the former installation with Christian package and reinstalled it with the CP780 driver, but it failed and I got the same error message. Neither printer switch on/off nor system restart helped.
Now, I reinstalled Christians package. The printer were switched on/off and after system restart it worked. Great!!
Re-instalation of Christians package also helped to restore the printing capability on my iMac late 2013 where I installed the CP780 according to the link above in Mavericks earlier, but was upgraded to Yosemite recently. After the upgrade the printer did not work any more.
Can someone try to reproduce as follows on a "fresh machine"?
1. Download CP780 Lion driver from Canon.
2. Modify the package as described in the link above.
3. Install the modified package
4. Run Christians package
5. Switch off printer, restart the system and start the printer.
6. Evtl. delete and re-add printer in system settings
6. Print from iPhoto
Many thanks to Christian and Impact Imaging! Looking forward to your comments.
Keywords: How to install Canon Selphy CP780 on Yosemite