After upgrading from joomla 3.6.0 to joomla 3.6.1, joomla suddenly bakend page was blank.
try to enter to admisnitrator page, and get this error:
Se ha producido un error.
0 Failed to start the session: already started by PHP ($_SESSION is set).
Try suggestions from https://github.com/joomla/joomla-cms/pull/11430 but nothing changed.