When using the REST API, the href= attributes in the XML responses can be wrong, because they are hard-coded in jetbrains/buildServer/server/rest/request/Constants to begin with "/app/rest". That is only correct if your TeamCity server URL is something like http://tc.example.com/ or http://tc.example.com:8080/. We recently moved our server and changed its URL to something like https://tc.example.com/teamcity/, which broke our integration tools. The correct way to combine that URL with /app/rest/whatever produces https://tc.example.com/app/rest/whatever, not https://tc.example.com/teamcity/app/rest/whatever as is necessary. The REST API needs to be changed to produce the correct href= attributes.