Update fails: AJAX HTTP error occurred. undefined function update_sql()

An AJAX HTTP error occurred. HTTP Result Code: 200 Debugging information follows. Path: http://example.com/update.php?id=9&op=do StatusText: OK ResponseText: Fatal error: Call to undefined function update_sql() in /home/zzz/public_html/example.com/sites/all/modules/masquerade/masquerade.install on line 148

failure on update