Manager access

I have a problem with opening a database created before

Manager data is stored in SQLite database. However it appears the file you are attempting to open is not a SQLite database.

“This business database is not valid”

What edition of Manager - server, cloud, desktop?
What version?
What Operating System?

What version did you use before?
Where did they business file come from?
Have you a backup?

You need to provide a lot more information if you want any real help

@Bahruz_Gasimov See this post and the linked post Manager 20.9.89 conversion error - #6 by Patch