n8n-io/n8n · error · UserError

MCP server "${server.name}": URL blocked by SSRF policy - ${

Error message

MCP server "${server.name}": URL blocked by SSRF policy - ${result.error.message}

What it means

Error "MCP server "${server.name}": URL blocked by SSRF policy - ${result.error.message}" thrown in n8n-io/n8n.

Source

Thrown at packages/@n8n/instance-ai/src/mcp/mcp-client-manager.ts:244

			if (!server.url) continue;

			let parsed: URL;
			try {
				parsed = new URL(server.url);
			} catch {
				throw new UserError(`MCP server "${server.name}": invalid URL "${server.url}"`);
			}

			if (parsed.protocol !== 'http:' && parsed.protocol !== 'https:') {
				throw new UserError(
					`MCP server "${server.name}": only http(s) URLs are allowed, got "${parsed.protocol}"`,
				);
			}

			if (this.ssrfValidator) {
				const result = await this.ssrfValidator.validateUrl(server.url);
				if (!result.ok) {
					throw new UserError(
						`MCP server "${server.name}": URL blocked by SSRF policy - ${result.error.message}`,
					);
				}
			}
		}
	}

	private async connectAndListTools(
		configs: McpServerConfig[],
		clientKey: string,
		requireApproval: boolean,
		logger: Logger,
		source: string,
	): Promise<McpRegularToolsResult> {
		const client = new McpClient(
			buildNativeMcpConfigs(configs, requireApproval, this.options.onToolCallSettled),
		);
		this.clientsByKey.set(clientKey, client);

View on GitHub (pinned to 5ac6606e81)

When it happens

Trigger: Thrown at packages/@n8n/instance-ai/src/mcp/mcp-client-manager.ts:244 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/1b8f6b1b99cd12db. Report an issue: GitHub.