[SOLVED] Semantic Kernel OpenAIAssistantAgent GroupChat InvokeStreamingAsync NullReferenceException in swedencentral

Maybe you have the same issue or any idea how to fix this?!

I'm using Semantic Kernel (.net) to access an Azure AI Service with GPT-4o model deployed in swedencentral via an APIM. When I start a group Chat with several assistants (OpenAIAssistantAgent) I get a NullReferenceException

chat.AddChatMessage(new ChatMessageContent(AuthorRole.User, input));

chat.IsComplete = false;

await foreach (var response in chat.InvokeStreamingAsync())

Using InvokeAsync() instead works fine...

I have diagnostic settings configured for all related resources and have not a single error. First the assistants are added, then a thread is started, the user message is added and the last step in the logs is the threads/thread_..../runs .

Doing the same with a similar infrastructure in francecentral works fine (so far - as far as I know swedencentral ist updated earlier).

My "demo" solution is based on this example: https://learn.microsoft.com/en-us/semantic-kernel/frameworks/agent/examples/example-agent-collaboration?pivots=programming-language-csharp BUT uses OpenAIAssistantAgent

AssistantClient assistantClient = OpenAIAssistantAgent.CreateAzureOpenAIClient(
    new ApiKeyCredential(apiKey),
    new Uri(endpoint),
    httpClient: httpClient).GetAssistantClient();

Assistant agentReviewer = await assistantClient.CreateAssistantAsync(
    deploymentName, new AssistantCreationOptions()
    {
        Name = ReviewerName,
        Instructions =
            """
            ...
            """,
        Description = "Your responsibility is to review and identify how to improve user provided content.",
        
    });

OpenAIAssistantAgent assistantAgentReviewer = new OpenAIAssistantAgent(
    agentReviewer,
    assistantClient);

I tried semantic Kernel in version 1.45 and 1.47

Here my error callstack:

System.NullReferenceException: Object reference not set to an instance of an object.
   at OpenAI.AsyncSseUpdateCollection`1.AsyncSseUpdateEnumerator`1.System.Collections.Generic.IAsyncEnumerator<U>.MoveNextAsync()
   at OpenAI.AsyncSseUpdateCollection`1.GetValuesFromPageAsync(ClientResult page)+MoveNext()
   at OpenAI.AsyncSseUpdateCollection`1.GetValuesFromPageAsync(ClientResult page)+MoveNext()
   at OpenAI.AsyncSseUpdateCollection`1.GetValuesFromPageAsync(ClientResult page)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
   at System.ClientModel.AsyncCollectionResult`1.GetAsyncEnumerator(CancellationToken cancellationToken)+MoveNext()
   at System.ClientModel.AsyncCollectionResult`1.GetAsyncEnumerator(CancellationToken cancellationToken)+MoveNext()
   at System.ClientModel.AsyncCollectionResult`1.GetAsyncEnumerator(CancellationToken cancellationToken)+MoveNext()
   at System.ClientModel.AsyncCollectionResult`1.GetAsyncEnumerator(CancellationToken cancellationToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
   at Microsoft.SemanticKernel.Agents.OpenAI.Internal.AssistantThreadActions.InvokeStreamingAsync(OpenAIAssistantAgent agent, AssistantClient client, String threadId, IList`1 messages, RunCreationOptions invocationOptions, ILogger logger, Kernel kernel, KernelArguments arguments, CancellationToken cancellationToken)+MoveNext()
   at Microsoft.SemanticKernel.Agents.OpenAI.Internal.AssistantThreadActions.InvokeStreamingAsync(OpenAIAssistantAgent agent, AssistantClient client, String threadId, IList`1 messages, RunCreationOptions invocationOptions, ILogger logger, Kernel kernel, KernelArguments arguments, CancellationToken cancellationToken)+MoveNext()
   at Microsoft.SemanticKernel.Agents.OpenAI.Internal.AssistantThreadActions.InvokeStreamingAsync(OpenAIAssistantAgent agent, AssistantClient client, String threadId, IList`1 messages, RunCreationOptions invocationOptions, ILogger logger, Kernel kernel, KernelArguments arguments, CancellationToken cancellationToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
   at Microsoft.SemanticKernel.Diagnostics.ActivityExtensions.RunWithActivityAsync[TResult](Func`1 getActivity, Func`1 operation, CancellationToken cancellationToken)+MoveNext()
   at Microsoft.SemanticKernel.Diagnostics.ActivityExtensions.RunWithActivityAsync[TResult](Func`1 getActivity, Func`1 operation, CancellationToken cancellationToken)+MoveNext()
   at Microsoft.SemanticKernel.Diagnostics.ActivityExtensions.RunWithActivityAsync[TResult](Func`1 getActivity, Func`1 operation, CancellationToken cancellationToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
   at Microsoft.SemanticKernel.Agents.AgentChat.InvokeStreamingAgentAsync(Agent agent, CancellationToken cancellationToken)+MoveNext()
   at Microsoft.SemanticKernel.Agents.AgentChat.InvokeStreamingAgentAsync(Agent agent, CancellationToken cancellationToken)+MoveNext()
   at Microsoft.SemanticKernel.Agents.AgentChat.InvokeStreamingAgentAsync(Agent agent, CancellationToken cancellationToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
   at Microsoft.SemanticKernel.Agents.AgentGroupChat.InvokeStreamingAsync(Agent agent, CancellationToken cancellationToken)+MoveNext()
   at Microsoft.SemanticKernel.Agents.AgentGroupChat.InvokeStreamingAsync(Agent agent, CancellationToken cancellationToken)+MoveNext()
   at Microsoft.SemanticKernel.Agents.AgentGroupChat.InvokeStreamingAsync(Agent agent, CancellationToken cancellationToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
   at Microsoft.SemanticKernel.Agents.AgentGroupChat.InvokeStreamingAsync(CancellationToken cancellationToken)+MoveNext()
   at Microsoft.SemanticKernel.Agents.AgentGroupChat.InvokeStreamingAsync(CancellationToken cancellationToken)+MoveNext()
   at Microsoft.SemanticKernel.Agents.AgentGroupChat.InvokeStreamingAsync(CancellationToken cancellationToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()