microsoft/semantic-kernel · error · ArgumentException

Response is null

Error message

Response is null

What it means

Thrown by BedrockTextGenerationClient when InvokeModelAsync returned a response that is null or whose Body is null (non-throwing but empty). It is an ArgumentException guarding the GetInvokeResponseBody parse step in the text-generation (InvokeModel) path.

Source

Thrown at dotnet/src/Connectors/Connectors.Amazon/Bedrock/Core/Clients/BedrockTextGenerationClient.cs:110

            if (activity is not null)
            {
                activity.SetError(ex);
                if (response != null)
                {
                    activityStatus = BedrockClientUtilities.ConvertHttpStatusCodeToActivityStatusCode(response.HttpStatusCode);
                    activity.SetStatus(activityStatus);
                }
                else
                {
                    // If response is null, set a default status or leave it unset
                    activity.SetStatus(ActivityStatusCode.Error); // or ActivityStatusCode.Unset
                }
            }
            throw;
        }
        if ((response == null) || (response.Body == null))
        {
            throw new ArgumentException("Response is null");
        }
        activityStatus = BedrockClientUtilities.ConvertHttpStatusCodeToActivityStatusCode(response.HttpStatusCode);
        activity?.SetStatus(activityStatus);
        IReadOnlyList<TextContent> textResponse = this._ioTextService.GetInvokeResponseBody(response);
        activity?.SetCompletionResponse(textResponse);
        return textResponse;
    }

    internal async IAsyncEnumerable<StreamingTextContent> StreamTextAsync(
        string prompt,
        PromptExecutionSettings? executionSettings = null,
        Kernel? kernel = null,
        [EnumeratorCancellation] CancellationToken cancellationToken = default)
    {
        Verify.NotNullOrWhiteSpace(prompt);
        var requestBody = this._ioTextService.GetInvokeModelRequestBody(this._modelId, prompt, executionSettings);
        var invokeRequest = new InvokeModelWithResponseStreamRequest
        {

View on GitHub (pinned to c028a0c7dc)

Solutions

1. Confirm modelId is a Bedrock text-generation model and is enabled in the region.
2. Retry once on this ArgumentException; empty bodies can be transient.
3. Wrap the text-generation call in try/catch (ArgumentException) and log modelId + region.
4. Check the model's content-filter/guardrail configuration.

Example fix

// before
var text = await textGen.GetTextContentAsync("prompt", settings);

// after
try
{
    var text = await textGen.GetTextContentAsync("prompt", settings);
}
catch (ArgumentException ex) when (ex.Message == "Response is null")
{
    throw new InvalidOperationException($"Bedrock returned an empty body for text model '{modelId}'.", ex);
}

try { var text = await textGen.GetTextContentAsync(prompt, settings, ct); }
catch (ArgumentException ex) when (ex.Message == "Response is null")
{ throw new InvalidOperationException($"Bedrock returned an empty body for text model '{modelId}'.", ex); }

When it happens

Trigger: Text generation (non-streaming) call where the Bedrock InvokeModel response had no Body. Occurs with a model id the runtime accepts but returns an empty body for, content-policy interventions, or transient empty responses.

Common situations: Using a non-text model id in the text-generation path. Model not enabled in region. Content filter emptying the response. Transient transport anomaly.

Related errors

• Response failed
• Response is null
• An error occurred while initializing the {nameof(BedrockText
• Message role must be either Assistant or User.
• runtimeClient

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/77f6cd7d2b1731f4. Report an issue: GitHub.