I restarted TaskPaper this evening and was presented with a dialog box saying I only had 5 days on my trial. The dialog box presented three choices: Cancel, Activate License, and Buy Now. I looked up my license number and tried Activate License. I got the dreaded “Error” error message. Tried twice, same result.
I then opened the taskList.taskpaper document itself (not the app) and the app opened the document. I chose to Recover License in case I had an incorrect version. Then I chose Show License (which was blank), entered my email and license number.
It worked. All is well.