Although there hasn't been a lot of reports on it, some folks who have updated to BlackBerry 10.2.1 have been having issues with the Print To Go app crashing. If you fall into that category, the solution is easy enough. As noted by Michael Clewley on Twitter:
That's it, the issue should be fixed. Most people likely have tried this already but skipping the rebooting of your device part but really, that's the most important part. Let us know if it works for you in the comments.