Occurring for ALL Users:
1. Check that there is hard drive space on the server(s). Please see this article for server requirements.
2. Make sure the SQL Agent service is running and set to Automatic start up.
3. Verify custom AD fields have been correctly added to the web.config file. Please reference this article for more information.
4. Verify the application pool the portal is using is set to the identity account.
5. Verify the LDAP server the portal communicates with is online and accessible to the portal server.
6. Verify the identity account is not locked out of AD.
7. Recycle the application pool or reboot the server, if possible, and the recycle does not resolve the message.
8. Verify that the login information is correct for the SQL user and that the SQL user isn't locked out.
9. If you have updated your portal from 4.12-5.0 to the latest version (6.1.7), please check that your default.aspx file matches the file attached. Please note that if you overwrite the file with the contents of the attached file, you will lose the branding on your login page.
Occurring for ONE/SOME Users:
1. If using AD fields or Windows authentication, check that the username is the same in the portal as it is in AD.