Warning: undercode () cannot modify header - Line 192 and Line 1740

[mashayo]

I also get the following error when filtering search results by cities.

Warning: urldecode() expects parameter 1 to be string, array given in /home3/sitename/public_html/oc-includes/osclass/classes/Rewrite.php on line 192

Warning: Cannot modify header information - headers already sent by (output started at /home3/sitename/public_html/oc-includes/osclass/utils.php:1737) in /home3/chuokrbx/public_html/oc-includes/osclass/utils.php on line 1740.

This is under url: http://www.sitename.com/index.php?page=search&sOrder=dt_pub_date&iOrderType=desc&sPattern=&sRegion=&sCity=london&sPriceMin=&sPriceMax=&sCategory%5B%5D=3

Please assist.