[BUG] Serialization error with AI Agents: Unable to cast object of type 'd__2' to type

[karthiksimplist]

Library name and version

Azure.AI.Agents.Persistent 1.2.0-beta.4

Describe the bug

Message: Unable to cast object of type 'd__2' to type 'System.Collections.Generic.List`1[System.Text.Json.JsonElement]'.

Stack:
   at System.Text.Json.JsonSerializer.UnboxOnWrite[T](Object value)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.SerializeAsObject(Utf8JsonWriter writer, Object rootValue)
   at System.Text.Json.JsonSerializer.WriteStringAsObject(Object value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize(Object value, JsonTypeInfo jsonTypeInfo)
   at Azure.AI.Agents.Persistent.ThreadMessages.CreateMessageAsync(String threadId, MessageRole role, IEnumerable`1 contentBlocks, IEnumerable`1 attachments, IReadOnlyDictionary`2 metadata, CancellationToken cancellationToken)
   at Microsoft.SemanticKernel.Agents.AzureAI.Internal.AgentThreadActions.CreateMessageAsync(PersistentAgentsClient client, String threadId, ChatMessageContent message, CancellationToken cancellationToken)
   at Microsoft.SemanticKernel.Agents.AzureAI.AzureAIAgentThread.OnNewMessageInternalAsync(ChatMessageContent newMessage, CancellationToken cancellationToken)
   at Microsoft.SemanticKernel.Agents.AgentThread.OnNewMessageAsync(ChatMessageContent newMessage, CancellationToken cancellationToken)
   at Microsoft.SemanticKernel.Agents.Agent.EnsureThreadExistsWithMessagesAsync[TThreadType](ICollection`1 messages, AgentThread thread, Func`1 constructThread, CancellationToken cancellationToken)
   at Microsoft.SemanticKernel.Agents.AzureAI.AzureAIAgent.InvokeStreamingAsync(ICollection`1 messages, AgentThread thread, AzureAIAgentInvokeOptions options, CancellationToken cancellationToken)+MoveNext()
   at Microsoft.SemanticKernel.Agents.AzureAI.AzureAIAgent.InvokeStreamingAsync(ICollection`1 messages, AgentThread thread, AzureAIAgentInvokeOptions options, CancellationToken cancellationToken)+System.Threading.Tasks.Sources.IValueTaskSource.GetResult()

Expected behavior

Throws this exception all the time when using Microsoft.SemanticKernel.Agents.AzureAI.AzureAIAgent.InvokeStreamingAsync
which used to work on the same codebase of ours.

Actual behavior

Throws the above mentioned exception.

Reproduction Steps

Invoke
Microsoft.SemanticKernel.Agents.AzureAI.AzureAIAgent.InvokeStreamingAsync method with the following packages.

<PackageReference Include="Azure.AI.Agents.Persistent" Version="1.2.0-beta.4" />
<PackageReference Include="Azure.AI.OpenAI" Version="2.3.0-beta.1" />
<PackageReference Include="Azure.AI.Projects" Version="1.0.0-beta.11" />
<PackageReference Include="System.ClientModel" Version="1.6.1" />
<PackageReference Include="System.Linq.Async" Version="6.0.3" />
<PackageReference Include="Simplist.Framework.Services.Core" Version="1.0.0" />
<PackageReference Include="Simplist.Framework.Bootstrap" Version="1.0.0" />
<PackageReference Include="Microsoft.SemanticKernel" Version="1.64.0" />
<PackageReference Include="Microsoft.SemanticKernel.Core" Version="1.64.0" />
<PackageReference Include="Microsoft.SemanticKernel.Agents.Core" Version="1.64.0" />
<PackageReference Include="Microsoft.SemanticKernel.Agents.OpenAI" Version="1.64.0-preview" />
<PackageReference Include="Microsoft.SemanticKernel.Agents.AzureAI" Version="1.64.0-preview" />
<PackageReference Include="Microsoft.SemanticKernel.Plugins.Web" Version="1.64.0-alpha" />

Environment

.NET