When running a report on SSRS get error related to ASPState

We have reports on production on SSRS Sql Server reporting services

the reports were running correctly till yasterday! today when running any report get this error

Cannot open database "ASPState" requested by the login. The login failed. Login failed for user 'NT AUTHORITY\NETWORK SERVICE'.

why is this and how to solve it

If you were running fine until yesterday, then odds are something changed in your settings in IIS that has you logging in anonymously instead of impersonating someone, or the "NT AUTHORITY\NETWORK SERVICE" used to have a user on your SQL server, and it was changed or removed. Or that user's rights were changed. Or something.

You should probably ask around to see if anyone changed any settings or configurations on either IIS or SQL Server.