wp-includes/PHPMailer/SMTP.php:1453Reports an error number and string.
$errnoint$errmsgstring$errfilestringoptional''$errlineintoptional0 protected function errorHandler($errno, $errmsg, $errfile = '', $errline = 0) { $notice = 'Connection failed.'; $this->setError( $notice, $errmsg, (string) $errno ); $this->edebug( "$notice Error #$errno: $errmsg [$errfile line $errline]", self::DEBUG_CONNECTION ); }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/PHPMailer/SMTP.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.