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:
- Go to Programs and Features => Turn Windows Features On or Off
- Disable WebDAV Publishing under Internet Information Services => World Wide Web Services => Common HTTP Features
- 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>