Otter ProGe::ensure- package throws error

when I use proget::ensure-package I get jsonreaderexception error.? The type of feed didn't matter. if I use nuget.exe, it's installed successfully.
am I missing something? here is the error.

Unhandled exception: Newtonsoft.Json.JsonReaderException: Unexpected character encountered while parsing value: <. Path '', line 0, position 0.
at Newtonsoft.Json.JsonTextReader.ParseValue()
at Newtonsoft.Json.JsonTextReader.Read()
at Newtonsoft.Json.JsonReader.ReadAndMoveToContent()
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ReadForType(JsonReader reader, JsonContract contract, Boolean hasConverter)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)
at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)
at Newtonsoft.Json.JsonSerializer.Deserialize[T](JsonReader reader)
at Inedo.Otter.Extensions.Operations.ProGet.ProGetClient.<GetPackageInfoAsync>d__10.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 System.Runtime.CompilerServices.TaskAwaiter1.GetResult() at Inedo.Otter.Extensions.Operations.ProGet.EnsurePackageOperation.<CollectAsync>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 System.Runtime.CompilerServices.TaskAwaiter1.GetResult()
at Inedo.Otter.PlanExecuter.OtterPlanExecuterBase.<PerformCollection>d__45.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 Inedo.Otter.PlanExecuter.OtterPlanExecuterBase.<Inedo-ExecutionEngine-Executer-IExecutionHostEnvironment-ExecuteActionAsync>d__44.MoveNext()

Based on the error message, it looks like you are pointing to an invalid endpoint.

Note this will only work with a Universal feed type; not NuGet feed type.

Can you share the OtterScript of the plan that's causing the error?

Thank you Alana,
this makes sense. I was trying to use a NuGet feed type. This answers my question.