URGENT HELP NEEDED- file is being modified outside illustrator

[ShermaineB.]

Hi there! I read the other post about this related issue however none of it helps mine. I am currently using the latest version of illustrator 2021 and I did not update my MacBook (macOS Big Sur version 11.1) however I am receiving errors that the file is being modified outside illustrator and then it showed me an unknown error occurred. I tried to change the name and save it, resave it without an internet connect however, none of it works!! It still gives me the same error. PLEASE HELP 😞 I need to save this file for my thesis project

[Monika Gause]

Exactly where are you saving your files?

Exactly which filetype?

Does it work when you save as?

Do you also lose data?