siyuan-note/siyuan · error

url is required for http server

Error message

url is required for http server

What it means

Precondition check in connectHTTP: the server is configured with Type == "http" but server.URL is empty. The MCP StreamableClientTransport requires an Endpoint, so the function bails out before constructing the transport. This is a pure configuration defect.

Source

Thrown at kernel/mcp/client/mcp.go:616

	}
	sort.Slice(ret, func(i, j int) bool {
		left, right := strings.ToUpper(ret[i]), strings.ToUpper(ret[j])
		if left == right {
			return ret[i] < ret[j]
		}
		return left < right
	})
	return ret
}

// MCPEnvironmentVariables 返回当前内核环境变量名称和新服务默认允许继承的名称，不暴露变量值。
func MCPEnvironmentVariables() (names, defaults []string) {
	return environmentVariableNames(os.Environ(), runtime.GOOS), defaultMCPEnvironmentNames(runtime.GOOS)
}

func connectHTTP(ctx context.Context, client *mcp.Client, server conf.MCPServer, interactive bool) (*mcp.ClientSession, *exec.Cmd, *mcpOAuthHandler, error) {
	if server.URL == "" {
		return nil, nil, nil, fmt.Errorf("url is required for http server")
	}

	transport := &mcp.StreamableClientTransport{
		Endpoint: server.URL,
	}
	var oauthHandler *mcpOAuthHandler
	if !hasAuthorizationHeader(server.Headers) {
		oauthHandler = newMCPOAuthHandler(server, interactive)
		transport.OAuthHandler = oauthHandler
	}
	// 所有 MCP HTTP 出站请求统一带上 SiYuan UA，便于第三方 MCP server 识别客户端身份
	uaBase := httpclient.NewUserAgentRoundTripper(http.DefaultTransport)
	if len(server.Headers) > 0 {
		transport.HTTPClient = &http.Client{
			Transport: &headerRoundTripper{
				base:    uaBase,
				headers: server.Headers,
			},

View on GitHub (pinned to 251596fc0d)

Solutions

1. Set server.URL to the full MCP HTTP endpoint (e.g. https://example.com/mcp).
2. If the server is a local command, change server.Type to "stdio" and fill server.Command instead of URL.
3. Validate the config in the UI before save: if Type == "http", require a non-empty URL.

Example fix

// before
{"type": "http", "url": ""}
// after
{"type": "http", "url": "https://mcp.example.com/sse"}

func validateHTTPServer(server conf.MCPServer) error {
    if server.Type == "http" && server.URL == "" {
        return errors.New("http server requires a URL")
    }
    return nil
}

func isHTTPServerConfigured(s conf.MCPServer) bool {
    return s.Type == "http" && strings.TrimSpace(s.URL) != ""
}

When it happens

Trigger: connectHTTP(server) is called for a server whose Type is "http" and URL field is unset/empty. This happens when the user created an HTTP server entry but left the URL blank, or set the type incorrectly (the server is actually stdio).

Common situations: User picked 'http' as the server type in the UI but did not fill in the endpoint URL; config migration left URL empty; user actually meant a stdio server and selected the wrong type.

Related errors

• environment: %w
• name is empty
• invalid name %q
• duplicate inherited variable %q
• variable %q contains NUL

AI-assisted analysis of siyuan-note/siyuan@251596fc0d (2026-08-12). Data as JSON: /api/errors/5c10c2f67d5ce2e1. Report an issue: GitHub.