Unable to delete modules after updating
From Joomla! Documentation
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.
What is the cause[edit]
When a site is upgraded to 3.2, users are unable to delete modules and are shown a generic "An error has occurred" message.
How to fix[edit]
In order to delete modules, you will first need to open the module(s) you want to delete for editing and save them. After this, you will be able to delete the module(s).