I have a user who always gets this message on startup (first line translated from French):
"The project on your computer could not be opened.
Project guid must be set before adding it to the ScrTextCollection."
Since this is similar to the BYZ error (
https://paratext.org/ufaqs/corrupt-slt-resource-9-1/), I followed the instructions there: I closed Paratext (9.4, latest beta), moved the 3 source resources (BYZ, GRK, HEB) out of the _Resources folder, uninstalled Paratext, installed Paratext 9.4 (and then the patch to .5), verified that the source resources had been reinstalled in the _Resources folder, then started Paratext - same error.
So what "project" is it referring to? The user has also closed her Text Collection, and rebuilt it from scratch. But even if the Text Collection window is closed, the error still appears on Paratext startup.