.Net: System.InvalidOperationException: Collection was modified; enumeration operation may not execute from...

The 'Collection was modified; enumeration operation may not execute' error from Semantic Kernel on .NET was a runtime-version problem: the reporter was on .NET Core 3.1, which is out of support. On .NET 6, 7, or 8, mutating the dictionary in that code path is fine (the key always exists, so the dictionary doesn't grow). If you hit this, upgrade your runtime; it stays an issue only on .NET Framework.

Source: gh:microsoft/semantic-kernel#6058 (Semantic Kernel)

In gh:microsoft/semantic-kernel#6058, the issue was: Describe the bug I try upgrading from 1.7.1 but any version above that I tried are throwing exceptions when I am using GetChatMessageContentsAsync. If using GetStreamingChatMessageContentsAsync with the exact same parameters everything is working fine. I am using Azure Open AI with a few kernel plugins and ToolCallBehavior = ToolCallBehavior.AutoInvokeKernelFunctions,. System.InvalidOperationException: Collection was modified; enumeration operation may not execute. at System.Collections.Generic.Dictionary`2.Enumerator.MoveNext() at Microsoft.SemanticKernel.Connectors.OpenAI.ClientCore.. The verified answer: The 'Collection was modified; enumeration operation may not execute' error from Semantic Kernel on .NET was a runtime-version problem: the reporter was on .NET Core 3.1, which is out of support. On .NET 6, 7, or 8, mutating the dictionary in that code path is fine (the key always exists, so the dictionary doesn't grow). If you hit this, upgrade your runtime; it stays an issue only on .NET Framework.. Issue URL: https://github.com/microsoft/semantic-kernel/issues/6058