Symptoms

When creating or editing an issue, the exception "The Field is Required" is not being displayed.  

Cause

When submitting an empty required field, the action will resulted in a 400 Bad Request exception.

Resolution

1. Open the web.config that's in the folder you setup in IIS for JIRA.

2. Add the following lines within the file

   <system.webServer>
       <httpErrors errorMode="Detailed" />
   </system.webServer>