Printing Problem - But only in web browsers

Under Yosemite 10.10.5 on an iMac, I get the following two error messages when printing from Firefox and also when using "Save as pdf" in Firefox:

First error message: "Print Preview Error. An error occurred while printing"

Then, after clicking OK, I get the following second error message: "Printer Error. An error occurred while printing"

And, of course nothing is printed.

The Preview app, in general, seems to be working fine. And printing from other apps (not browsers) is also fine.

What I’ve tried:

• Tried printing under Safari and Chrome. Both yield just one empty page - most of the time. Sometimes they print properly. Possibly because of some of the stuff below ?
• Tried printing from other apps. All work fine.
• Tried removing com.apple.print.custompresets.forprinter.Canon_MX922.plist No impact.
• Repaired permissions - no impact
• Restarted in Safe mode. Then restarted. No impact
• Opened console and searched for "preview" Got the following:
  mdworker(456) deny file-read-data /Applications/Preview.app
• Reset the printing system using apple instructions at support.apple.com/en-ca/HT201539 No impact on problem
• Updated Firefox to latest version (44.0) No impact on problem