Ton of TaskCanceledExeception and IOException during tool call without error #1156

andrew-vdb · 2026-01-18T15:03:03Z

andrew-vdb
Jan 18, 2026

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Is anyone see their debug output log during tool call?

The application itself working, ai do tool call, get response, is there a way i can know where is this exceptions coming from?

From mcp server side

ModelContextProtocol.Server.McpServer: Information: Server ({Redacted} 1.0.0.0), Client ({Redacted} 1.0.0.0) method 'tools/call' request handler completed.
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Net.Http.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Net.Http.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Http.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Http.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Http.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
The thread 42280 has exited with code 0 (0x0).
The thread '.NET TP Worker' (48376) has exited with code 0 (0x0).
The thread '.NET TP Worker' (1488) has exited with code 0 (0x0).
The thread '.NET TP Worker' (17668) has exited with code 0 (0x0).
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.OperationCanceledException' in System.Private.CoreLib.dll

From ai/client side

Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Net.Http.dll
System.Net.Http.HttpClient.mcp-tool-client.ClientHandler: Information: Received HTTP response headers after 43.8028ms - 200
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
System.Net.Http.HttpClient.mcp-tool-client.LogicalHandler: Information: End processing HTTP request after 88.7753ms - 200
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
The thread '.NET TP Worker' (24580) has exited with code 0 (0x0).
The thread '.NET TP Worker' (46640) has exited with code 0 (0x0).
The thread '.NET TP Worker' (40080) has exited with code 0 (0x0).
The thread '.NET TP Worker' (15136) has exited with code 0 (0x0).
Exception thrown: 'System.IO.IOException' in System.Net.Sockets.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Security.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Sockets.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Security.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Sockets.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Security.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
The thread '.NET TP Worker' (50212) has exited with code 0 (0x0).
Exception thrown: 'System.IO.IOException' in System.Net.Sockets.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Security.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Sockets.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Security.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
The thread '.NET TP Worker' (22092) has exited with code 0 (0x0).
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Net.Http.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Http.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Net.Http.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Http.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Net.Http.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll
Exception thrown: 'System.IO.IOException' in System.Private.CoreLib.dll

PederHP · 2026-01-18T16:35:33Z

PederHP
Jan 18, 2026
Collaborator

You can enable first-chance exceptions in your debugger / IDE and catch those exceptions to look at the call stacks.

Do you have a reproducible sample for this issue?

0 replies

andrew-vdb · 2026-01-18T17:15:25Z

andrew-vdb
Jan 18, 2026
Author

let me try that....

no, dont have repro

1 reply

andrew-vdb Jan 18, 2026
Author

Hereby Opus finding, its also answer weird DELETE request i saw in the log, i will test updating to 0.6

Summary

You're on 0.4.1-preview.1, and there's a newer version 0.6.0-preview.1 available. The SDK has had ongoing work on disposal and session management issues.

The root cause: The MCP SDK uses SSE (Server-Sent Events) which maintains a persistent HTTP connection. When McpClient.DisposeAsync() is called, it:

Cancels internal CancellationTokenSource
Tries to send a DELETE request to terminate the session
Closes the SSE connection

If the SSE read loop is still active when disposal happens, the cancellation triggers TaskCanceledException or IOException as the connection is torn down.

This is a known SDK behavior, not a bug in your code. The v0.4.0-preview.2 release notes mention "Fix slow shutdown when a Streamable HTTP client is connected" which suggests
they've been working on this.

Recommendations

Upgrade the SDK to 0.6.0-preview.1 - it may have improved disposal handling
If exceptions persist after upgrade, suppressing TaskCanceledException, OperationCanceledException, and IOException during disposal is the appropriate pattern since these are
expected when forcibly closing SSE connections

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Ton of TaskCanceledExeception and IOException during tool call without error #1156

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andrew-vdb Jan 18, 2026

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Replies: 2 comments · 1 reply

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PederHP Jan 18, 2026 Collaborator

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andrew-vdb Jan 18, 2026 Author

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andrew-vdb
Jan 18, 2026

Replies: 2 comments 1 reply

PederHP
Jan 18, 2026
Collaborator

andrew-vdb
Jan 18, 2026
Author

andrew-vdb Jan 18, 2026
Author