Symptoms

Initial setup for the application server had only database.
The path for the FileStorage was added to the settings later.
After the above change, the following error appears when opening the project from the Application Server: “Unable to access Project's options. This object is corrupt ()”.

Cause

The issue “Unable to access Project's options. This object is corrupt ()” is caused by changing Database and FileStorage settings in the Administration & Monitoring console.

An important point here is that it is not possible to add FS afterward: 
 
A file storage can only be created when creating a database and cannot be created later while processing documents with ABBYY FlexiCapture. You also won't be able to disconnect the file storage you connected when creating the database.
 
More information about you can be found at the following link: https://help.abbyy.com/en-us/flexicapture/12/admin_guide/create_database/.
To elaborate a bit more regarding this, FlexiCapture has been set to look for project options in Database, after adding a path to FileStorage, FlexiCapture tries to find project settings and files there, but didn't find anything.

Resolution

If you would like to migrate from Database schema to Database+FileStorage schema, please consider the following actions: 

1. Remove the File Storage path from settings, to make the project available again
2. Export projects from the server to some local storage manually or by DownloadProject
3. Create a new Database with FileStorage enabled
4. Upload previously exported projects to a new Database