Cannot login, get a warning…

I just upgraded and I cannot login to my dashboard. Instead the page reads:

Warning: Cannot modify header information – headers already sent by (output started at /home/content/t/a/j/tajharia/html/wp-includes/general-template.php:269) in /home/content/t/a/j/tajharia/html/wp-includes/pluggable.php on line 868

Per the advice given on all of the other similar posts, I have already deleted the empty lines at the end of these files, and have reloaded wordpress entirely. How do I get my blog back?

Thanks,
-Tajharia.