Cannot create a new page

Once I click Publish, got the following error:

Warning: stripos() expects parameter 1 to be string, array given in /home/kavideo/public_html/wp-includes/formatting.php on line 3774

Warning: Cannot modify header information – headers already sent by (output started at /home/kavideo/public_html/wp-includes/formatting.php:3774) in /home/kavideo/public_html/wp-admin/post.php on line 197

Warning: Cannot modify header information – headers already sent by (output started at /home/kavideo/public_html/wp-includes/formatting.php:3774) in /home/kavideo/public_html/wp-includes/pluggable.php on line 1179

~~~~

Here’s what I see in the line 3774 of formatting.php:

if ( 0 !== stripos( $url, ‘mailto:’ ) ) {
$strip = array(‘%0d’, ‘%0a’, ‘%0D’, ‘%0A’);
$url = _deep_replace($strip, $url);

Thought it was related to an old version, but the upgrade to the latest one, didn’t help.
BTW Got one more error after the upgrade: Warning: Error while sending QUERY packet. PID=578125 in /home/kavideo/public_html/wp-includes/wp-db.php on line 1879

Please advise.

Thank you!