Cannot connect to GitHub MCP

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Posted on by JM-10061055-0

Cannot connect to GitHub MCP. COnnection is established. But I get error:

Error Message: Knowledge failed with a runtime error MCP server response could not be deserialized as JSON. Response content: event: message data: {"jsonrpc":"2.0","id":"1","result":{"capabilities":{"completions":{},"prompts":{},"resources":{},"tools":{}},"protocolVersion":"2024-11-05","serverInfo":{"name":"github-mcp-server","title":"GitHub MCP Server","version":"github-mcp-server/remote-1ee9a31f31c68953c043aacd9337a2d468f302e6","icons":[{"src":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABgAAAAYCAYAAADgdz34AAAABmJLR0QA/wD/AP+gvaeTAAADK0lEQVRIibWVQWhcVRSGv3Pfy0zGdBIMRWk7iziMTpORptpqiNSNG1dNizaFFlxIoYuCC7NwJdiVlhYpr... Error Code: ConnectorActionException Conversation Id: f248f113-f718-420e-9de1-e08c156e6759 Time (UTC): 2026-03-12T11:01:21.379Z

So it seems that GitHub responses in SSE format but Copilot is expecting JSON ... I do not see any settings to correct this.

Thanks,
Jan

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Model context protocol

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Valantis 1,723 on at

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Hi @JM-10061055-0 ,

You're right - GitHub's MCP server is responding in SSE (Server-Sent Events) format, but Copilot Studio expects plain JSON.

Copilot Studio only supports Streamable HTTP transport. SSE support was deprecated after August 2025. Since GitHub's MCP server is sending SSE format (event: message data: {...}), Copilot Studio can't parse it.

try this fix:

You need GitHub's MCP server to use Streamable HTTP instead of SSE. Check if GitHub provides a different endpoint:

SSE endpoint (what you're using now): https://.../sse or /runtime/webhooks/mcp/sse

HTTP endpoint (what you need): https://.../mcp or /runtime/webhooks/mcp

Try changing the MCP server URL in Copilot Studio to the HTTP endpoint.

If GitHub only provides SSE:

You'll need a conversion layer:

Deploy an Azure Function that receives SSE from GitHub and converts to HTTP JSON-RPC

Use API Management to transform the response format

Check if GitHub has an updated MCP server with HTTP support

test:

Use curl or Postman to hit the endpoint directly. If you see text/event-stream with event: and data: lines, it's SSE. You need to find or create an HTTP endpoint that returns plain application/json.

https://learn.microsoft.com/microsoft-copilot-studio/mcp-add-existing-server-to-agent

https://learn.microsoft.com/azure/container-apps/mcp-troubleshooting

Best regards,

Valantis

✅ If this helped solve your issue, please Accept as Solution so others can find it quickly.

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🏷️ For follow-ups @Valantis.

📝 https://valantisond365.com/

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JM-10061055-0 7 on at

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Hi,

I cannot modify URL of the tool used in and advertised by Copilot Studio. There is just connection to GitHub and I can't edit it in any way even not in Power Platform. Still just showing it is ok. I guess it is up on Microsoft to set this up as holder of both platforms now. Thanks, Jan

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