The URL 'Shared Documents/filename' is invalid. It may refer to a nonexistent file or folder, or refer to a valid file or folder that is not in the current Web.

After the RBS Installation was complete and I was trying to upload a file to the document library, I got this error

Sorry, something went wrong

The URL 'Shared Documents/filename' is invalid.  It may refer to a nonexistent file or folder, or refer to a valid file or folder that is not in the current Web.

Reason

Permission issue for uploading files to the content database

How to fix this

I added the application pool account for the web application as dbowner to the content DB where RBS was implemented.This fixed the issue