sudden fcp x error messages (storage location not available / failed to save. unknown store type, format, or version)

i have been working on a project for a month with no issues (i got osx catalina). i paused for a week,

and realized when i opened fcpx again that it had been updated. now i suddenly run into issues.

the library and entire project are on my harddrive (not an external one), and have not been moved or renamed in any way. i have 600gb of free storage.

a couple of minutes after i open my project, i get the following message:

"final cut pro cannot save changes to "trailer_5" the storage location for one or more libraries is no longer available. the libraries will be closed so no work is lost"

there is no option to do anything, it just closes the library.

i tried to create a new library for a different clip after that, and got the following pop-up:

"failed to save. unknown store type, format, or version."

i deleted all fcpx preferences, in case i had messed up something there unintentionally, but to no avail.

i am a newbie and just learning how to use the program, but i am 100% sure i did not change anything in final cut or on my computer since i last worked on the project. help? thank you!