After upgrading from 1.9 to 1.11 I had got the error message “Your access level is insufficient to run this script” when trying to log in.
The problem was TTRSS needed to run some upgrade script but if you log in as a non admin user straight after an install it will throw this error. The best thing to do is log in as an admin user so that it can do the upgrade.
The alternative is to update the security level of the user trying to log in using SQL:
update ttrss_users set access_level=10 where login = '[username]';
where [username] should be replaced by the username used to log in.