I am using Joomla 2.5.8 . Actually after i install a new theme this error occurred \"JHtml: :jquery not supported. File not found\" . Since i am new on Joomla i was unable to fi
JHtmlJquery is not a class in Joomla! 2.5, it was introduced in 3.0 with the other UI changes. Odds are the extension you've installed is designed for Joomla! 3.0 and later.
Locate the line that the code being used to import jQuery and make sure it shows the following:
JHtml::_('jquery.framework');
Which imports it in noConflict mode, but is also for Joomla 3.x only
Else you can replace it with the following, which will detect if a jQuery library is already being loaded and if not, it will import it.
if (!JFactory::getApplication()->get('jquery'))
{
JFactory::getApplication()->set('jquery',true);
JFactory::getDocument()->addScript('http://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js');
}