Unsupported MCP protocol version: 2025-03-26

[tomhoad]

Our MCP server requires MCP protocol version 2025-11-25. Visual Studio Code GitHub Copilot Chat seems to not support this (yet?):

"Unsupported MCP protocol version: 2025-03-26. Supported versions: [2025-11-25]"

• Copilot Chat Extension Version: 0.43.0
• VS Code Version: 1.115.0
• OS Version: MacOS Sequoia 15.7.5
• Feature (e.g. agent/edit/ask mode): Ask
• Selected model (e.g. GPT 4.1, Claude 3.7 Sonnet): Auto
• Logs:

2026-04-09 12:44:43.101 [info] Starting server agentcore
2026-04-09 12:44:43.101 [info] Connection state: Starting
2026-04-09 12:44:43.101 [info] Starting server from LocalProcess extension host
2026-04-09 12:44:43.101 [info] Connection state: Running
2026-04-09 12:44:43.320 [info] Discovered resource metadata at https://<redacted>.gateway.bedrock-agentcore.eu-west-1.amazonaws.com/.well-known/oauth-protected-resource
2026-04-09 12:44:43.320 [info] Using auth server metadata url: https://<redacted>.okta.com/oauth2/default
2026-04-09 12:44:44.848 [warning] Error fetching authorization server metadata: Error: Failed to fetch authorization server metadata from https://<redacted>.okta.com/.well-known/oauth-authorization-server/oauth2/default: 405 {"errorCode":"E0000022","errorSummary":"The endpoint does not support the provided HTTP method","errorLink":"E0000022","errorId":"x","errorCauses":[]}
2026-04-09 12:44:44.848 [warning] Error fetching authorization server metadata: Error: Failed to fetch authorization server metadata from https://<redacted>.okta.com/.well-known/openid-configuration/oauth2/default: 405 {"errorCode":"E0000022","errorSummary":"The endpoint does not support the provided HTTP method","errorLink":"E0000022","errorId":"x","errorCauses":[]}
2026-04-09 12:44:44.849 [info] Discovered authorization server metadata at https://<redacted>okta.com/oauth2/default/.well-known/openid-configuration
2026-04-09 12:44:48.224 [info] Waiting for server to respond to `initialize` request...
2026-04-09 12:44:53.105 [info] Waiting for server to respond to `initialize` request...
2026-04-09 12:44:58.105 [info] Waiting for server to respond to `initialize` request...
2026-04-09 12:45:03.105 [info] Waiting for server to respond to `initialize` request...
2026-04-09 12:45:08.103 [info] Waiting for server to respond to `initialize` request...
2026-04-09 12:45:13.104 [info] Waiting for server to respond to `initialize` request...
2026-04-09 12:45:14.129 [info] Connection state: Error 400 status sending message to https://<redacted>.gateway.bedrock-agentcore.eu-west-1.amazonaws.com/mcp: {"jsonrpc":"2.0","id":2,"error":{"code":-32600,"message":"Unsupported MCP protocol version: 2025-03-26. Supported versions: [2025-11-25]"}}

Steps to Reproduce:

1. Configure remote MCP server that requires OAuth flow:

"agentcore": {
      "type": "http",
      "url": "https://<redacted>.gateway.bedrock-agentcore.eu-west-1.amazonaws.com/mcp",
    }

2. Complete OAuth flow

3. VSCode successful callback screen is seen:

4. Error log above seen

[TylerLeonhardt]

@connor4312 from the logs, I don't think this is MCP Auth related so passing to you.

[connor4312]

Please Developer: Set Log Level > Trace and share MCP server logs with that set. Thanks!

[tomhoad]

@connor4312 Below are the server logs that show the OAuth process and tools/list request.

Interestingly it seems like VS Code initialised the session with the 2025-11-25 version, but the later request for tools/list seems to fail, complaining about a version mismatch.

Does the client use the 2025-11-25 protocol version for all subsequent requests, not just the initialisation?

{
    "resource_arn": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
    "event_timestamp": 1776087292083,
    "body": {
        "isError": true,
        "log": "Missing Bearer token",
        "id": "0"
    },
    "account_id": "___",
    "request_id": "310cbcda-e77a-4206-92ff-d3d198011730",
    "trace_id": "69dcf0fc6d1247f57c1a17e370c3ca04",
    "span_id": "9b55c9bb02a6c13e",
    "resource": {
        "attributes": {
            "service.name": "___",
            "cloud.resource_id": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
            "cloud.platform": "aws_bedrock_agentcore"
        }
    },
    "attributes": {
        "aws.request.id": "310cbcda-e77a-4206-92ff-d3d198011730",
        "aws.account.id": "___",
        "aws.resource.type": "AWS::BedrockAgentCore::Gateway"
    },
    "timeUnixNano": 1776087292083642140,
    "severityNumber": 17,
    "severityText": "ERROR",
    "traceId": "69dcf0fc6d1247f57c1a17e370c3ca04",
    "spanId": "9b55c9bb02a6c13e"
}
{
    "resource_arn": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
    "event_timestamp": 1776087331411,
    "body": {
        "isError": false,
        "log": "Started processing request",
        "requestBody": "{id=1, jsonrpc=2.0, method=initialize, params={clientInfo={name=Visual Studio Code, version=1.115.0}, protocolVersion=2025-11-25, capabilities={elicitation={form={}, url={}}, extensions={io.modelcontextprotocol/ui={mimeTypes=[text/html;profile=mcp-app]}}, roots={listChanged=true}, tasks={list={}, cancel={}, requests={elicitation={create={}}, sampling={createMessage={}}}}, sampling={}}}}",
        "id": "1"
    },
    "account_id": "___",
    "request_id": "24fbc2e7-89c6-4cd3-b5c2-bb12da01994f",
    "trace_id": "69dcf12365a3023b1df08d0827cbe00e",
    "span_id": "ac8c4d9a8fcd521e",
    "resource": {
        "attributes": {
            "service.name": "___",
            "cloud.resource_id": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
            "cloud.platform": "aws_bedrock_agentcore"
        }
    },
    "attributes": {
        "aws.request.id": "24fbc2e7-89c6-4cd3-b5c2-bb12da01994f",
        "aws.account.id": "___",
        "aws.resource.type": "AWS::BedrockAgentCore::Gateway"
    },
    "timeUnixNano": 1776087331411079312,
    "severityNumber": 9,
    "severityText": "INFO",
    "traceId": "69dcf12365a3023b1df08d0827cbe00e",
    "spanId": "ac8c4d9a8fcd521e"
}
{
    "resource_arn": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
    "event_timestamp": 1776087331414,
    "body": {
        "isError": false,
        "log": "Received request for initialize method",
        "id": "1"
    },
    "account_id": "___",
    "request_id": "24fbc2e7-89c6-4cd3-b5c2-bb12da01994f",
    "trace_id": "69dcf12365a3023b1df08d0827cbe00e",
    "span_id": "ac8c4d9a8fcd521e",
    "resource": {
        "attributes": {
            "service.name": "___",
            "cloud.resource_id": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
            "cloud.platform": "aws_bedrock_agentcore"
        }
    },
    "attributes": {
        "aws.request.id": "24fbc2e7-89c6-4cd3-b5c2-bb12da01994f",
        "aws.account.id": "___",
        "aws.resource.type": "AWS::BedrockAgentCore::Gateway"
    },
    "timeUnixNano": 1776087331414857536,
    "severityNumber": 9,
    "severityText": "INFO",
    "traceId": "69dcf12365a3023b1df08d0827cbe00e",
    "spanId": "ac8c4d9a8fcd521e"
}
{
    "resource_arn": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
    "event_timestamp": 1776087331417,
    "body": {
        "isError": false,
        "responseBody": "{jsonrpc=2.0, id=1, result={protocolVersion=2025-11-25, capabilities={tools={listChanged=false}}, serverInfo={version=1.0.0, name=___}}}",
        "log": "Successfully processed request",
        "id": "1"
    },
    "account_id": "___",
    "request_id": "24fbc2e7-89c6-4cd3-b5c2-bb12da01994f",
    "trace_id": "69dcf12365a3023b1df08d0827cbe00e",
    "span_id": "ac8c4d9a8fcd521e",
    "resource": {
        "attributes": {
            "service.name": "___",
            "cloud.resource_id": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
            "cloud.platform": "aws_bedrock_agentcore"
        }
    },
    "attributes": {
        "aws.request.id": "24fbc2e7-89c6-4cd3-b5c2-bb12da01994f",
        "aws.account.id": "___",
        "aws.resource.type": "AWS::BedrockAgentCore::Gateway"
    },
    "timeUnixNano": 1776087331417755326,
    "severityNumber": 9,
    "severityText": "INFO",
    "traceId": "69dcf12365a3023b1df08d0827cbe00e",
    "spanId": "ac8c4d9a8fcd521e"
}
{
    "resource_arn": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
    "event_timestamp": 1776087331541,
    "body": {
        "isError": false,
        "log": "Started processing request",
        "requestBody": "{method=notifications/initialized, jsonrpc=2.0}",
        "id": "0"
    },
    "account_id": "___",
    "request_id": "a4358536-d080-45a8-bc4a-334ec8439683",
    "trace_id": "69dcf1237ae3ae0853bcc00209754a08",
    "span_id": "37e1a84342bab518",
    "resource": {
        "attributes": {
            "service.name": "___",
            "cloud.resource_id": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
            "cloud.platform": "aws_bedrock_agentcore"
        }
    },
    "attributes": {
        "aws.request.id": "a4358536-d080-45a8-bc4a-334ec8439683",
        "aws.account.id": "___",
        "aws.resource.type": "AWS::BedrockAgentCore::Gateway"
    },
    "timeUnixNano": 1776087331541643027,
    "severityNumber": 9,
    "severityText": "INFO",
    "traceId": "69dcf1237ae3ae0853bcc00209754a08",
    "spanId": "37e1a84342bab518"
}
{
    "resource_arn": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
    "event_timestamp": 1776087331542,
    "body": {
        "isError": false,
        "log": "Received request for notifications/initialized method",
        "id": "0"
    },
    "account_id": "___",
    "request_id": "a4358536-d080-45a8-bc4a-334ec8439683",
    "trace_id": "69dcf1237ae3ae0853bcc00209754a08",
    "span_id": "37e1a84342bab518",
    "resource": {
        "attributes": {
            "service.name": "___",
            "cloud.resource_id": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
            "cloud.platform": "aws_bedrock_agentcore"
        }
    },
    "attributes": {
        "aws.request.id": "a4358536-d080-45a8-bc4a-334ec8439683",
        "aws.account.id": "___",
        "aws.resource.type": "AWS::BedrockAgentCore::Gateway"
    },
    "timeUnixNano": 1776087331542749413,
    "severityNumber": 9,
    "severityText": "INFO",
    "traceId": "69dcf1237ae3ae0853bcc00209754a08",
    "spanId": "37e1a84342bab518"
}
{
    "resource_arn": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
    "event_timestamp": 1776087331590,
    "body": {
        "isError": false,
        "log": "Started processing request",
        "requestBody": "{id=2, jsonrpc=2.0, method=tools/list, params={}}",
        "id": "2"
    },
    "account_id": "___",
    "request_id": "7cb96c9a-8754-458a-af02-43e0d324d454",
    "trace_id": "69dcf1230b2656fd6b679c0a02290953",
    "span_id": "7d22ac6715fb32a5",
    "resource": {
        "attributes": {
            "service.name": "___",
            "cloud.resource_id": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
            "cloud.platform": "aws_bedrock_agentcore"
        }
    },
    "attributes": {
        "aws.request.id": "7cb96c9a-8754-458a-af02-43e0d324d454",
        "aws.account.id": "___",
        "aws.resource.type": "AWS::BedrockAgentCore::Gateway"
    },
    "timeUnixNano": 1776087331590786662,
    "severityNumber": 9,
    "severityText": "INFO",
    "traceId": "69dcf1230b2656fd6b679c0a02290953",
    "spanId": "7d22ac6715fb32a5"
}
{
    "resource_arn": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
    "event_timestamp": 1776087331592,
    "body": {
        "isError": true,
        "log": "Unsupported MCP protocol version: 2025-03-26. Supported versions: [2025-11-25]",
        "id": "2"
    },
    "account_id": "___",
    "request_id": "7cb96c9a-8754-458a-af02-43e0d324d454",
    "trace_id": "69dcf1230b2656fd6b679c0a02290953",
    "span_id": "7d22ac6715fb32a5",
    "resource": {
        "attributes": {
            "service.name": "___",
            "cloud.resource_id": "arn:aws:bedrock-agentcore:eu-west-1:___:gateway/___",
            "cloud.platform": "aws_bedrock_agentcore"
        }
    },
    "attributes": {
        "aws.request.id": "7cb96c9a-8754-458a-af02-43e0d324d454",
        "aws.account.id": "___",
        "aws.resource.type": "AWS::BedrockAgentCore::Gateway"
    },
    "timeUnixNano": 1776087331592345486,
    "severityNumber": 17,
    "severityText": "ERROR",
    "traceId": "69dcf1230b2656fd6b679c0a02290953",
    "spanId": "7d22ac6715fb32a5"
}

[connor4312]

Does the client use the 2025-11-25 protocol version for all subsequent requests, not just the initialisation?

Subsequent requests do not include the tool version, only the initialize handshake does. VS Code implements the 2025-11-25. I wanted trace logs from the client to verify what's happening, but most likely this is a service issue.

[tomhoad]

@connor4312 Thanks for taking a look. These are the full trace logs generated by VS Code.

By "service issue" do you mean AgentCore? I don't think this is the case - according to the spec:

If using HTTP, the client MUST include the MCP-Protocol-Version: HTTP header on all subsequent requests to the MCP server. For details, see the Protocol Version Header section in Transports.

2026-04-13 16:23:24.198 [info] Starting server agentcore
2026-04-13 16:23:24.199 [info] Connection state: Starting
2026-04-13 16:23:24.199 [info] Starting server from LocalProcess extension host
2026-04-13 16:23:24.199 [info] Connection state: Running
2026-04-13 16:23:24.199 [debug] [editor -> server] {"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-11-25","capabilities":{"roots":{"listChanged":true},"sampling":{},"elicitation":{"form":{},"url":{}},"tasks":{"list":{},"cancel":{},"requests":{"sampling":{"createMessage":{}},"elicitation":{"create":{}}}},"extensions":{"io.modelcontextprotocol/ui":{"mimeTypes":["text/html;profile=mcp-app"]}}},"clientInfo":{"name":"Visual Studio Code","version":"1.115.0"}}}
2026-04-13 16:23:24.209 [trace] Fetching https://___/mcp with options: {"method":"POST","headers":{"Content-Type":"application/json","Content-Length":"439","Accept":"text/event-stream, application/json","user-agent":"Visual Studio Code/1.115.0"},"body":"{\"jsonrpc\":\"2.0\",\"id\":1,\"method\":\"initialize\",\"params\":{\"protocolVersion\":\"2025-11-25\",\"capabilities\":{\"roots\":{\"listChanged\":true},\"sampling\":{},\"elicitation\":{\"form\":{},\"url\":{}},\"tasks\":{\"list\":{},\"cancel\":{},\"requests\":{\"sampling\":{\"createMessage\":{}},\"elicitation\":{\"create\":{}}}},\"extensions\":{\"io.modelcontextprotocol/ui\":{\"mimeTypes\":[\"text/html;profile=mcp-app\"]}}},\"clientInfo\":{\"name\":\"Visual Studio Code\",\"version\":\"1.115.0\"}}}"}
2026-04-13 16:23:24.360 [trace] Fetched https://___/mcp: {"status":401,"headers":{"connection":"keep-alive","content-length":"81","content-type":"application/json","date":"Mon, 13 Apr 2026 15:23:24 GMT","www-authenticate":"Bearer resource_metadata=\"https://___/.well-known/oauth-protected-resource\"","x-amzn-remapped-content-type":"application/json","x-amzn-requestid":"6a889b19-368a-4e66-a222-9e9778b10e72"}}
2026-04-13 16:23:24.360 [debug] Found resource_metadata challenge in WWW-Authenticate header: https://___/.well-known/oauth-protected-resource
2026-04-13 16:23:24.360 [trace] Fetching https://___/.well-known/oauth-protected-resource with options: {"method":"GET","headers":{"Accept":"application/json","MCP-Protocol-Version":"2025-11-25","user-agent":"Visual Studio Code/1.115.0"}}
2026-04-13 16:23:24.442 [trace] Fetched https://___/.well-known/oauth-protected-resource: {"status":200,"headers":{"connection":"keep-alive","content-length":"189","content-type":"application/json","date":"Mon, 13 Apr 2026 15:23:24 GMT","x-amzn-requestid":"70e45e68-ca78-47da-a65c-36fedb1eb7c3"}}
2026-04-13 16:23:24.442 [info] Discovered resource metadata at https://___/.well-known/oauth-protected-resource
2026-04-13 16:23:24.442 [info] Using auth server metadata url: https://___/oauth2/default
2026-04-13 16:23:24.442 [debug] Fetching auth server metadata for: https://___/oauth2/default ...
2026-04-13 16:23:24.442 [trace] Fetching https://___/.well-known/oauth-authorization-server/oauth2/default with options: {"method":"GET","headers":{"Accept":"application/json","user-agent":"Visual Studio Code/1.115.0"}}
2026-04-13 16:23:25.016 [trace] Fetched https://___/.well-known/oauth-authorization-server/oauth2/default: {"status":405,"headers":{"connection":"keep-alive","content-type":"application/json","date":"Mon, 13 Apr 2026 15:23:24 GMT","server":"nginx","strict-transport-security":"max-age=315360000; includeSubDomains","transfer-encoding":"chunked","x-content-type-options":"nosniff"}}
2026-04-13 16:23:25.016 [trace] Fetching https://___/.well-known/openid-configuration/oauth2/default with options: {"method":"GET","headers":{"Accept":"application/json","user-agent":"Visual Studio Code/1.115.0"}}
2026-04-13 16:23:25.665 [trace] Fetched https://___/.well-known/openid-configuration/oauth2/default: {"status":405,"headers":{"connection":"keep-alive","content-type":"application/json","date":"Mon, 13 Apr 2026 15:23:25 GMT","server":"nginx","strict-transport-security":"max-age=315360000; includeSubDomains","transfer-encoding":"chunked","x-content-type-options":"nosniff"}}
2026-04-13 16:23:25.665 [trace] Fetching https://___/oauth2/default/.well-known/openid-configuration with options: {"method":"GET","headers":{"Accept":"application/json","user-agent":"Visual Studio Code/1.115.0"}}
2026-04-13 16:23:25.837 [trace] Fetched https://___/oauth2/default/.well-known/openid-configuration: {"status":200,"headers":{"accept-ch":"Sec-CH-UA-Platform-Version","cache-control":"max-age=86400, must-revalidate","connection":"keep-alive","content-security-policy":"default-src 'self' ___ *.oktacdn.com; connect-src 'self' ___ ___-admin.okta.com *.oktacdn.com *.mixpanel.com *.mapbox.com ___.kerberos.okta.com ___.mtls.okta.com *.authenticatorlocalprod.com:8769 http://localhost:8769 http://127.0.0.1:8769 *.authenticatorlocalprod.com:65111 http://localhost:65111 http://127.0.0.1:65111 *.authenticatorlocalprod.com:65121 http://localhost:65121 http://127.0.0.1:65121 *.authenticatorlocalprod.com:65131 http://localhost:65131 http://127.0.0.1:65131 *.authenticatorlocalprod.com:65141 http://localhost:65141 http://127.0.0.1:65141 *.authenticatorlocalprod.com:65151 http://localhost:65151 http://127.0.0.1:65151 https://oinmanager.okta.com data: *.ingest.sentry.io; script-src 'unsafe-inline' 'self' 'report-sample' ___ *.oktacdn.com; style-src 'unsafe-inline' 'self' 'report-sample' ___ *.oktacdn.com; frame-src 'self' ___ ___-admin.okta.com login.okta.com *.vidyard.com com-okta-authenticator:; img-src 'self' ___ *.oktacdn.com *.tiles.mapbox.com *.mapbox.com *.vidyard.com data: blob:; font-src 'self' ___ data: *.oktacdn.com fonts.gstatic.com; frame-ancestors 'self'","content-type":"application/json","date":"Mon, 13 Apr 2026 15:23:25 GMT","expires":"Tue, 14 Apr 2026 15:23:25 GMT","p3p":"CP=\"HONK\"","referrer-policy":"strict-origin-when-cross-origin","server":"nginx","strict-transport-security":"max-age=315360000; includeSubDomains","transfer-encoding":"chunked","vary":"Origin","x-content-type-options":"nosniff","x-okta-request-id":"d1148cf55f03c4f7f174acdd6d3e0305","x-xss-protection":"0"}}
2026-04-13 16:23:25.838 [warning] Error fetching authorization server metadata: Error: Failed to fetch authorization server metadata from https://___/.well-known/oauth-authorization-server/oauth2/default: 405 {"errorCode":"E0000022","errorSummary":"The endpoint does not support the provided HTTP method","errorLink":"E0000022","errorId":"oaegljYYFBXQ2a8TXIEEPDZFg","errorCauses":[]}
2026-04-13 16:23:25.838 [warning] Error fetching authorization server metadata: Error: Failed to fetch authorization server metadata from https://___/.well-known/openid-configuration/oauth2/default: 405 {"errorCode":"E0000022","errorSummary":"The endpoint does not support the provided HTTP method","errorLink":"E0000022","errorId":"oaeP5g0E_V5QQOnRFcmb5EPyg","errorCauses":[]}
2026-04-13 16:23:25.838 [info] Discovered authorization server metadata at https://___/oauth2/default/.well-known/openid-configuration
2026-04-13 16:23:29.200 [info] Waiting for server to respond to `initialize` request...
2026-04-13 16:23:31.595 [trace] Fetching https://___/mcp with options: {"method":"POST","headers":{"Content-Type":"application/json","Content-Length":"439","Accept":"text/event-stream, application/json","user-agent":"Visual Studio Code/1.115.0","Authorization":"***"},"body":"{\"jsonrpc\":\"2.0\",\"id\":1,\"method\":\"initialize\",\"params\":{\"protocolVersion\":\"2025-11-25\",\"capabilities\":{\"roots\":{\"listChanged\":true},\"sampling\":{},\"elicitation\":{\"form\":{},\"url\":{}},\"tasks\":{\"list\":{},\"cancel\":{},\"requests\":{\"sampling\":{\"createMessage\":{}},\"elicitation\":{\"create\":{}}}},\"extensions\":{\"io.modelcontextprotocol/ui\":{\"mimeTypes\":[\"text/html;profile=mcp-app\"]}}},\"clientInfo\":{\"name\":\"Visual Studio Code\",\"version\":\"1.115.0\"}}}"}
2026-04-13 16:23:31.825 [trace] Fetched https://___/mcp: {"status":200,"headers":{"connection":"keep-alive","content-length":"178","content-type":"application/json","date":"Mon, 13 Apr 2026 15:23:31 GMT","x-amzn-remapped-content-type":"application/json","x-amzn-requestid":"e0dcd075-8eac-42fd-bd12-bc147c4eeee3"}}
2026-04-13 16:23:31.825 [debug] [server -> editor] {"jsonrpc":"2.0","id":1,"result":{"protocolVersion":"2025-11-25","capabilities":{"tools":{"listChanged":false}},"serverInfo":{"version":"1.0.0","name":"___"}}}
2026-04-13 16:23:31.825 [debug] [editor -> server] {"method":"notifications/initialized","jsonrpc":"2.0"}
2026-04-13 16:23:31.826 [debug] [editor -> server] {"jsonrpc":"2.0","id":2,"method":"tools/list","params":{}}
2026-04-13 16:23:31.828 [trace] Fetching https://___/mcp with options: {"method":"POST","headers":{"Content-Type":"application/json","Content-Length":"54","Accept":"text/event-stream, application/json","Authorization":"***","user-agent":"Visual Studio Code/1.115.0"},"body":"{\"method\":\"notifications/initialized\",\"jsonrpc\":\"2.0\"}"}
2026-04-13 16:23:31.830 [trace] Fetching https://___/mcp with options: {"method":"GET","headers":{"Accept":"text/event-stream","Authorization":"***","user-agent":"Visual Studio Code/1.115.0"}}
2026-04-13 16:23:31.836 [trace] Fetching https://___/mcp with options: {"method":"POST","headers":{"Content-Type":"application/json","Content-Length":"58","Accept":"text/event-stream, application/json","Authorization":"***","user-agent":"Visual Studio Code/1.115.0"},"body":"{\"jsonrpc\":\"2.0\",\"id\":2,\"method\":\"tools/list\",\"params\":{}}"}
2026-04-13 16:23:31.895 [trace] Fetched https://___/mcp: {"status":405,"headers":{"connection":"keep-alive","content-length":"18","content-type":"text/plain; charset=utf-8","date":"Mon, 13 Apr 2026 15:23:31 GMT","server":"awselb/2.0"}}
2026-04-13 16:23:31.895 [debug] 405 status connecting to https://___/mcp for async notifications; they will be disabled: Method Not Allowed
2026-04-13 16:23:31.951 [trace] Fetched https://___/mcp: {"status":202,"headers":{"connection":"keep-alive","content-length":"0","content-type":"application/json","date":"Mon, 13 Apr 2026 15:23:31 GMT","x-amzn-remapped-content-type":"application/json","x-amzn-requestid":"2068b78a-2156-45c2-92e4-6d0885178d7a"}}
2026-04-13 16:23:31.980 [trace] Fetched https://___/mcp: {"status":400,"headers":{"connection":"keep-alive","content-length":"139","content-type":"application/json","date":"Mon, 13 Apr 2026 15:23:32 GMT","x-amzn-remapped-content-type":"application/json","x-amzn-requestid":"a2284753-02e9-4a76-ba42-5029ffe61d7e"}}
2026-04-13 16:23:31.980 [info] Connection state: Error 400 status sending message to https://___/mcp: {"jsonrpc":"2.0","id":2,"error":{"code":-32600,"message":"Unsupported MCP protocol version: 2025-03-26. Supported versions: [2025-11-25]"}}

[connor4312]

Ah, that is probably the source of the issue. We do not do that -- and I guess no other MCP server has actually depended on that yet! Will fix for the next release.