What MCP Streamable HTTP protocol version does Copilot Studio send during initialize?

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Posted on by AA-29041637-0

Hi everyone,

I'm connecting a vendor-managed MCP server to Copilot Studio using Streamable HTTP and API key auth through a Tool. The connection gets created fine, but tool discovery fails with a -32603 internal error and does not show any tools.

After some digging, I found that the MCP server requires a minimum protocol version of 2025-06-18, but from what I can tell, Copilot Studio sends 2024-11-05 in the initialize request based on an older thread in this forumn

Has anyone been able to confirm what protocol version Copilot Studio currently uses? And is there any way to change it or any update planned?

The vendor's MCP server is fully managed (we just enable it and get an API key), so we can't change anything on the server side.

Thanks in advance.

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11manish 2,432 on at

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It seems that Copilot Studio currently uses an older MCP protocol version (around 2024-11-05) when sending the initialize request.

If your vendor MCP server requires a newer version such as 2025-06-18, tool discovery will fail due to protocol incompatibility, often resulting in a -32603 error.

At present, Copilot Studio does not provide a way to configure or override the MCP protocol version.

The only viable workarounds are either to introduce a proxy that translates between protocol versions or to request backward compatibility support from the

vendor’s MCP server.

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Prasad-MSFT Microsoft Employee on at

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You are correct: as of now, Copilot Studio’s MCP integration sends a protocol version of 2024-11-05 in the initialize request. This is currently the latest version supported by Copilot Studio, and there is no supported way to change or override the protocol version from the client side.

Key points:

If your vendor’s MCP server requires a minimum protocol version of 2025-06-18, Copilot Studio will not be able to connect or discover tools, resulting in the -32603 internal error you’re seeing.

The protocol version is hardcoded in Copilot Studio and updated only when Microsoft releases a new platform update.

There is no configuration or setting in Copilot Studio to specify a newer protocol version.

What you can do:

Contact your vendor and ask if they can temporarily support the 2024-11-05 protocol version until Copilot Studio updates.

Monitor the Microsoft Copilot Studio release notes and community forums for announcements about protocol version updates.

Submit feedback to Microsoft via the Copilot Studio feedback channels to request support for the newer protocol version.

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