Method Not Allowed when calling Post using the Build api - tfs

Question

I am using TFS2018 and calling the build api like this
internal void UpdateSourceBranches(List<BuildDefinition> defs)
{
using (var handler = new HttpClientHandler { Credentials = new NetworkCredential(tfsUser, tfsPass) })
using (var client = new HttpClient(handler))
{
try
{
client.BaseAddress = new Uri(tfsServer);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
foreach (var def in defs)
{
var buildId = def.Id;
var sourceBranch = $"$/{def.Repository.Name}/{def.Project.Name}";
var parameters = new Dictionary<string, string> { { "BuildConfiguration", "release" },
{ "BuildPlatform", "x86|x64|ARM" },
{ "system.debug", "true" }
};
var jsonParams = JsonConvert.SerializeObject(parameters);
var content = new FormUrlEncodedContent(new[]
{
new KeyValuePair<string, string>("id", buildId.ToString()),
new KeyValuePair<string, string>("sourceBranch", sourceBranch),
new KeyValuePair<string, string>("parameters", jsonParams)
});
var response = client.PostAsync($"DefaultCollection/{def.Repository.Name}/_apis/build/builds?api-version=3.0-preview.1", content);
var s = response.Result;
}
}
catch (Exception ex)
{
}
}
}
But getting the following response
{StatusCode: 405, ReasonPhrase: 'Method Not Allowed', Version: 1.1,
Content: System.Net.Http.StreamContent, Headers: { Pragma: no-cache
X-TFS-ProcessId: ActivityId: X-TFS-Session: X-VSS-E2EID:
X-FRAME-OPTIONS: SAMEORIGIN X-VSS-UserData: :user Persistent-Auth:
true Lfs-Authenticate: NTLM X-Content-Type-Options: nosniff
Cache-Control: no-cache Date: Fri, 09 Mar 2018 14:37:16 GMT P3P:
CP="CAO DSP COR ADMa DEV CONo TELo CUR PSA PSD TAI IVDo OUR SAMi BUS
DEM NAV STA UNI COM INT PHY ONL FIN PUR LOC CNT" Server:
Microsoft-IIS/10.0 X-AspNet-Version: 4.0.30319 X-Powered-By: ASP.NET
Content-Length: 93 Allow: GET Content-Type: application/json;
charset=utf-8 Expires: -1 }}
Any idea why I am getting Method Not Allowed ?
Here is the bad response:
{StatusCode: 400, ReasonPhrase: 'Bad Request', Version: 1.1, Content:
System.Net.Http.StreamContent, Headers: { Pragma: no-cache
X-TFS-ProcessId: xxxxxx-xxxxx-xxxxx-xxxxxx-xxxxxxxxxx ActivityId:
xxxxxx-xxxxx-xxxxx-xxxxxx-xxxxxxxxxx X-TFS-Session:
xxxxxx-xxxxx-xxxxx-xxxxxx-xxxxxxxxxx X-VSS-E2EID:
xxxxxx-xxxxx-xxxxx-xxxxxx-xxxxxxxxxx X-FRAME-OPTIONS: SAMEORIGIN
X-VSS-UserData: xxxxxx-xxxxx-xxxxx-xxxxxx-xxxxxxxxxx:user
Persistent-Auth: true Lfs-Authenticate: NTLM
X-Content-Type-Options: nosniff Cache-Control: no-cache Date: Tue,
13 Mar 2018 09:21:53 GMT P3P: CP="...multiple keywords" Server:
Microsoft-IIS/10.0 X-AspNet-Version: 4.0.30319 X-Powered-By:
ASP.NET Content-Length: 547 Content-Type: application/json;
charset=utf-8 Expires: -1 }}

Answer 1

Sounds like your POST is the issue, try using a GET

Answer 2

You should use api-version=2.0 instead of 3.0-preview.1.
Update code snippet:
string con = "{\"definition\": {\"id\": 47},\"sourceBranch\":\"$/CeceScrum/TestCaseProject\",\"parameters\":\"{\\\"BuildConfiguration\\\":\\\"release\\\",\\\"BuildPlatform\\\":\\\"any cpu\\\",\\\"system.debug\\\":\\\"false\\\"}\"}";
var patchValue = new StringContent(con, Encoding.UTF8, "application/json");
HttpClient httpClient = new HttpClient();
string _credentials = Convert.ToBase64String(System.Text.ASCIIEncoding.ASCII.GetBytes(string.Format("{0}:{1}", "domain\\username", "password")));
httpClient.DefaultRequestHeaders.Accept.Clear();
httpClient.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", _credentials);
var method = new HttpMethod("POST");
var request = new HttpRequestMessage(method, "http://TFS2018:8080/tfs/DefaultCollection/CeceScrum/_apis/build/builds?api-version=2.0") { Content = patchValue };
httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = httpClient.SendAsync(request).Result;
string re= response.Content.ReadAsStringAsync().Result;