one50mph

i was having the same issue…this helped me fix the issue: https://wordpress.org/support/topic/plugin-yoast-google-analytics-save-settings-page-not-found

i too contacted my web host provider…they white-listed a rule that was causing the issue…i was able to authenticate successfully w/out having the page not found error pop up.

Hi,
Running WordPress 3.0.1. I applied update…then deleted it because WP installation got messed up. Now, I can’t login to Dashboard anymore…the following messages pop up…

Warning: Missing argument 2 for wp_widget() in /home/content/f/o/c/focusmediainc/html/wp-includes/widgets.php on line 76

Warning: Cannot modify header information – headers already sent by (output started at /home/content/f/o/c/focusmediainc/html/wp-includes/widgets.php:76) in /home/content/f/o/c/focusmediainc/html/wp-login.php on line 354

Warning: Cannot modify header information – headers already sent by (output started at /home/content/f/o/c/focusmediainc/html/wp-includes/widgets.php:76) in /home/content/f/o/c/focusmediainc/html/wp-login.php on line 366

Warning: Cannot modify header information – headers already sent by (output started at /home/content/f/o/c/focusmediainc/html/wp-includes/widgets.php:76) in /home/content/f/o/c/focusmediainc/html/wp-includes/pluggable.php on line 702

Warning: Cannot modify header information – headers already sent by (output started at /home/content/f/o/c/focusmediainc/html/wp-includes/widgets.php:76) in /home/content/f/o/c/focusmediainc/html/wp-includes/pluggable.php on line 703

Warning: Cannot modify header information – headers already sent by (output started at /home/content/f/o/c/focusmediainc/html/wp-includes/widgets.php:76) in /home/content/f/o/c/focusmediainc/html/wp-includes/pluggable.php on line 704

Warning: Cannot modify header information – headers already sent by (output started at /home/content/f/o/c/focusmediainc/html/wp-includes/widgets.php:76) in /home/content/f/o/c/focusmediainc/html/wp-includes/pluggable.php on line 897

Please advise. Thanks!