# User authorization exceptions

SQL exceptions are returned when errors occur with user authorizations.

Derby validates the database properties when you set the properties. An exception is returned if you specify an invalid value when you set these properties.

After you set the `derby.database.sqlAuthorization` property to TRUE, you cannot set the property back to FALSE.

If a user attempts to connect to a database but is not authorized to connect to that database, the SQLException 04501 is returned.

If a user with read-only access attempts to write to a database, the SQLException 08004 `- connection refused` is returned.

Parent topic: Setting the SQL standard authorization mode
Related concepts
Setting the default connection access mode
Setting the user authorizations for individual users
Setting the SQL standard authorization mode