I have the same problem and have tried you solution it didn’t work for me.
Warning: Missing argument 2 for wp_widget() in /home/content/m/e/t/metaweb/html/wp-includes/widgets.php on line 76
Warning: Cannot modify header information – headers already sent by (output started at /home/content/m/e/t/metaweb/html/wp-includes/widgets.php:76) in /home/content/m/e/t/metaweb/html/wp-includes/pluggable.php on line 890
I have also tried replacing the widgets.php and pluggable.php
I still am unable to log in and get a different error.
I welcome any useful suggestions you may have.
