VSTS Nuget push: 400 (Bad Request) - azure-artifacts

Question

I'm attempting to push to the Package portion of VSTS. I'm getting Bad Request back, but there's no further detail, which is very frustrating. Here is my request and the return.
nuget push -Source "MFS" package.nupkg -Verbosity detailed -ApiKey VSTS
NuGet Version: 3.5.0.1938
Pushing package.nupkg to 'https://instance.pkgs.visualstudio.com/_packaging/c59817c1-a3c5-4654-95cf-760c1ce56c62/nuget/v2/'...
PUT https://instance.pkgs.visualstudio.com/_packaging/c59817c1-a3c5-4654-95cf-760c1ce56c62/nuget/v2/
BadRequest https://instance.pkgs.visualstudio.com/_packaging/c59817c1-a3c5-4654-95cf-760c1ce56c62/nuget/v2/ 10597ms
System.AggregateException: One or more errors occurred. ---> System.Net.Http.HttpRequestException: Response status code does not indicate success: 400 (Bad Request).
at System.Net.Http.HttpResponseMessage.EnsureSuccessStatusCode()
at NuGet.Protocol.Core.Types.PackageUpdateResource.<>c.<PushPackageToServer>b__19_1(HttpResponseMessage response)
at NuGet.Protocol.HttpSource.<ProcessResponseAsync>d__14`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NuGet.Protocol.Core.Types.PackageUpdateResource.<PushPackageToServer>d__19.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NuGet.Protocol.Core.Types.PackageUpdateResource.<PushPackageCore>d__13.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NuGet.Protocol.Core.Types.PackageUpdateResource.<PushPackage>d__12.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NuGet.Protocol.Core.Types.PackageUpdateResource.<Push>d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NuGet.Commands.PushRunner.<Run>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NuGet.CommandLine.PushCommand.<ExecuteCommandAsync>d__28.MoveNext()
--- End of inner exception stack trace ---
at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
at NuGet.CommandLine.Command.Execute()
at NuGet.CommandLine.Program.MainCore(String workingDirectory, String[] args)
---> (Inner Exception #0) System.Net.Http.HttpRequestException: Response status code does not indicate success: 400 (Bad Request).
at System.Net.Http.HttpResponseMessage.EnsureSuccessStatusCode()
at NuGet.Protocol.Core.Types.PackageUpdateResource.<>c.<PushPackageToServer>b__19_1(HttpResponseMessage response)
at NuGet.Protocol.HttpSource.<ProcessResponseAsync>d__14`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NuGet.Protocol.Core.Types.PackageUpdateResource.<PushPackageToServer>d__19.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NuGet.Protocol.Core.Types.PackageUpdateResource.<PushPackageCore>d__13.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NuGet.Protocol.Core.Types.PackageUpdateResource.<PushPackage>d__12.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NuGet.Protocol.Core.Types.PackageUpdateResource.<Push>d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NuGet.Commands.PushRunner.<Run>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NuGet.CommandLine.PushCommand.<ExecuteCommandAsync>d__28.MoveNext()<---
I was prompted to enter my username/password, which I assume was correct. There is no further data than this: no output logs, no Event logs, nothing. This is all I have to go on.
I tried removing the source and readding it, but I was not prompted to enter my credentials again, so if my credentials were somehow wrong, it's cached somewhere and I have no idea where.
TIA,
Matt

Answer 1

Figured it out. I had a folder at the nupkg's root, so all my files were actually 2 levels down. Once I brought the nuspec and other files to the root, it worked.

Answer 2

You'll need a -ApiKey {string} e.g. -ApiKey VSTS to push.

Answer 3

Rephrased to satisfy StackOverflow answer policy:
We see that the package pushed was invalid because it did not contain a file ending in .nuspec. You should open the nupkg as a zip file and confirm that the package contains a file ending with .nuspec.

Answer 4

TL;DR always add -ApiKey VSTS
I eventually figured it out, too.
I omitted the ApiKey since I was authenticating with my credentials, so why would I need a key? And I didn't know the key for our corporate VSTS.
The warning was being shown but I was ignoring it, thinking it was a general local NuGet.exe warning for whenever you make it push without a key.
Then I had a brainwave that actually the warning being shown is the header value and that it somehow needs a key just for no reason other than because it does.
So with a colleague and looking at the VSTS feed instructions itself, we saw -ApiKey VSTS in their sample and added that and still had to login, and bingo!