When you have upgraded from Joomla! 1.5.0,1.5.1,1.5.2 to 1.5.3 and on the front end receive the error Warning: Missing argument 1 for JDocumentHTML::getBuffer() and don’t know what to do. Follow the steps below in order to fix it.
Download the latest complete Joomla! 1.5.3 or later from the Joomla! Website, and locate the following file in the installation package /libraries/joomla/document/html/html.php
Copy the html.php and overwrite the existing file to your existing Joomla! installationto the following directory /public_html/libraries/joomla/document/html/ refresh yoursite and the error should be gone.