System.InvalidOperationException: Error deserializing GenAI message content.

[Juan Manuel Saad (juan-saad)]

Hi,
I'm building an Aspire application as a playground to test new Agent Framework's .NET SDK features and I started seeing this exception on Microsoft.CognitiveServices OpenTelemetry traces for LLM responses:

# Error displaying GenAI content:
System.InvalidOperationException: Error deserializing GenAI message content.
Error description: System.Text.Json.JsonException: The input does not contain any JSON tokens. Expected the input to start with a valid JSON token, when isFinalBlock is true. Path: $ | LineNumber: 0 | BytePositionInLine: 0.
Content description: SystemMessage event content for message #0

System.Text.Json.JsonException: The input does not contain any JSON tokens. Expected the input to start with a valid JSON token, when isFinalBlock is true. Path: $ | LineNumber: 0 | BytePositionInLine: 0.

System.Text.Json.JsonReaderException: The input does not contain any JSON tokens. Expected the input to start with a valid JSON token, when isFinalBlock is true. LineNumber: 0 | BytePositionInLine: 0.

I know there’s a chance I’m doing something odd in the code, but I was wondering whether this might be related to an Aspire or Agent Framework issue.

[Stephen Toub (stephentoub)]

Juan Manuel Saad (@juan-saad), can you elaborate on where you're seeing those exceptions? In the Aspire dashboard?

[Juan Manuel Saad (juan-saad)]

That's correct I can see it in Aspire Dashboard traces, where the LLM invocations are shown

[Stephen Toub (stephentoub)]

James Newton-King (@JamesNK)

[James Newton-King (JamesNK)]

What do you see when you click on details? It seems like there is message data with an empty string and a failure to deserialize it

[Juan Manuel Saad (juan-saad)]

I'm not being able to replicate it any longer, what I've seen in the details section within the events, several with empty responses. But that's only by clicking on the span instead of the "star" symbol. I will add more information once I can replicate it again