How to resolve 405 error occurred at the removal of field mappings

This 405 error can be caused after clicking the delete icon of the field mappings if IIS is not properly configured.

To resolve this you have two options:

I. Disable WebDAB Publishing:

1. Go to Programs and Features => Turn Windows Features On or Off
2. Disable WebDAV Publishing under Internet Information Services => World Wide Web Services => Common HTTP Features
   
   
3. Restart TFS4JIRA app pool in IIS Manager

II. Disable WebDAV Publishing in web.config file

As mentioned in https://stackoverflow.com/questions/49907423/side-effects-of-disabling-webdavmodule-in-asp-net-mvc-webapi

Just add those lines to web.config file located in the root folder of TFS4JIRA:

 <modules>
 <remove name="WebDAVModule"/>
 </modules>

 <handlers>
 <remove name="WebDAV"/>
 </handlers>