Editing module shows module XML data not available
From Joomla! Documentation
Joomla!
3.4.0
Some modules installed in Joomla 3.4 and higher (that worked in Joomla 3.3.6) show an error when attempting to edit.
Errors Reported[edit]
Module XML data not available when going to edit module (with no fields appearing).
Versions Affected[edit]
General Information
This pertains only to Joomla! version(s):- 3.4 and higher
What is the Cause?[edit]
Modules that have capital letters in their elements are now forced to lowercase during module installs (as a result of some standardisation in the installer). This results in case-sensitive systems with the XML file being unable to be found.
How to Fix[edit]
Ensure the module element
<filename module="mod_articles_category">mod_articles_category.php</filename>has no capital letters (as well as the appropriate XML file).