The vCenter UI service DefaultServlet must be set to "readonly" for "PUT" and "DELETE" commands.
The default servlet (or DefaultServlet) is a special servlet provided with Tomcat that is called when no other suitable page is found in a particular folder. The DefaultServlet serves static resources as well as directory listings. The DefaultServlet is configured by default with the "readonly" parameter set to "true" where HTTP commands such as "PUT" and "DELETE" are rejected.
Changing this to "false" allows clients to delete or modify static resources on the server and to upload new resources. DefaultServlet "readonly" must be set to "true", either literally or by absence (default).