@leocg
Yes, other browser (such as Firefox) works fine.
This problem may occured by memorized setting.
So, if we reset setting data of 'print by pdf', the problem may reliefed.

1. select print as pdf
2. select [More options] → set Margins = Custom
3. drag print preview frame, and size to narrower and lower

Then suddenly I got following dialog error
The selected printer is not available or not installed correctly. Check your printer or try selecting another printer.

This error could not recover for restart Opera.