These are few errors that frequently show up in my error log.
Catchable fatal error: Object of class WP_Error could not be converted to string in /home/hunt4fre/public_html/coupons/wp-content/plugins/wordpress-seo/frontend/class-frontend.php on line 490
PHP Warning: rtrim() expects parameter 1 to be string, object given in /home/hunt4fre/public_html/coupons/wp-includes/formatting.php on line 1250
PHP Catchable fatal error: Object of class WP_Error could not be converted to string in /home/hunt4fre/public_html/coupons/wp-includes/formatting.php on line 1250
Years ago Permalink structure was
I have changed that awhile back to /%postname%/ and was using Dean's Permalinks Migration plugin.
I have now disabled the plugin and have selected post name in the wordpress settings as I understand that wordpress will take care of these redirects.
I don't know if this makes a difference.