Why do I get 405 when trying to update a description?

[Oskar Wanderer]

https://dcmp-toolbox.atlassian.net/rest/api/3/issue/<issue>

Trying this 

{

    "fields" : {

        "description": "Description"

    }

}

or that

{

   "update": {

   "description": [

         {

            "set": "JIRA should also come with a free pony"

         }

      ]

   }

}

getting 405

What is wrong? 

[Dirk Ronsmans]

HTTP 405 means "Method not allowed"

Performing an update should be done using a "PUT" method, which one are you using? Perhaps POST?