Check:
Did you rename the admin directory?
Are you calling a file that actually is there?
Try the full url, ...www.theplace..., instead of ...theplace...
Check the file permissions, and possible directory permissions
Try some other files you know from your web control panel, as a comparison, is it the dir, or the file possibility
Don't want an index.php file with no read attribute.
Check the http:// vs. https://, never log to admin in http://, always use secure connection https://
Check that error message with your host, what does in mean options, because some errors are generated for other reasons, and given an eror number that may not be the actual reason.
Look at the url very closely, any typo mistakes? Bad syntax, etc?
Check password, and case sensitivity, need EXACT password
Check EXACT user name
Double check each retry rerequested login page AND MAKE SURE EACH TIME IT IS REFRESHED IT IS IN HTTPS// SECURE CONNECTION - EVERYTIME.
That is set in configuration php files, it's posted around
