Such glitches had happened before… too many times before. That’s why, when the problem first appeared, I assumed it was a temporary glitch with the Dymo software-completely unrelated to the OS X upgrade. You wouldn’t think that a minor OS X update, one that makes no mention of any printing-related changes, would precipitate this error. The little printer that couldn’t: The Dymo LabelWriter fails to connect Instead, an error message appeared that said the printer was “offline” or “not connected.” However, after I updated to OS X 10.9.4, I could no longer get any labels to print. The printer was working fine under OS X Mavericks 10.9.3. The surprising source of the failure is that the Dymo Label software is incompatible with the latest version of OS X. So, in some sense, the printer is still very much alive. Neither has there been any major shift in technology that would make the printer obsolete. As far as I can tell, all the hardware components remain in fine working order. My Dymo LabelWriter 400 Twin Turbo died last month.

Please see the solution at the bottom of the article.