Update: As of today, May 10th, the problem I described below on May 3rd 2017 has since magically fixed itself. Go figure. …
When I try to archive old projects/tasks, after selecting “File->Move old data to archive…”, changing the cutoff date, and selecting the “Move to archive” button, an alert pops up saying “Invalid external zip data identifier” and “Identifiers for external zip data must be non-empty”. Thinking perhaps the old archive was somehow corrupt I renamed it and tried again. I got the same message. OF did create a new archive file (~/Library/Containers/com.omnigroup.OmniFocus2.MacAppStore/Data/Library/Application Support/OmniFocusArchive.ofocus-archive).
I ‘googled’ it and fount nothing interesting. I think I need to open a ticket of OF support, but I thought it better to check here first. Perhaps I’m not holding my tongue out just right. ???