J3.x:Missing Installer Tabs
From Joomla! Documentation
Joomla!
3.6.0
Errors reported
After upgrading to Joomla 3.6.0, under certain circumstances, your installer tabs are missing (Install from file, Install from web, Install from folder etc..)
Versions affected
General Information
This pertains only to Joomla! version(s): 3.6.0
What is the cause
How to fix
CLEAR your cache, Clear your admin cache, Discover for new extensions, install the new plugins, enable the new plugins
See also: https://github.com/joomla/joomla-cms/issues/11098#issuecomment-232341213