Mintplex-Labs/anything-llm · error

MCP server is not currently running

Error message

MCP server ${name} is not currently running

What it means

Agent tool plugins are built once at boot from each MCP server's listTools() output, but the handler re-resolves the server at call time via a fresh MCPCompatibilityLayer and this.mcps[name]. If the server has since disconnected, crashed, or been removed from the connection map, that lookup fails and this error is thrown inside the tool handler; the surrounding catch converts it to a failure string the agent sees.

Solutions

1. Restart the MCP server / re-boot the hypervisor (toggle it in the agent MCP settings) so tools re-register against a live connection
2. Check the MCP server itself is reachable (curl the url, or run the stdio command manually)
3. Check server logs for the transport close/error events that preceded the tool call
4. Retry the agent turn after the server is back — stale tool registrations are refreshed on re-boot

const mcpLayer = new MCPCompatibilityLayer();
await mcpLayer.bootMCPServers(); // ensure connections exist
const server = mcpLayer.mcps[name];
if (!server) {
  return `${name} is offline — restart it in MCP settings before retrying.`;
}
const result = await server.callTool({ name: toolName, arguments: args });

function isMcpServerRunning(mcpLayer, name) {
  return !!mcpLayer.mcps[name] && typeof mcpLayer.mcps[name].callTool === 'function';
}

try {
  return await currentMcp.callTool({ name: tool.name, arguments: args });
} catch (error) {
  if (/not currently running/.test(error.message)) {
    // re-boot the hypervisor once, then retry the call before giving up
  }
  throw error;
}

When it happens

Trigger: The agent invokes an MCP tool (name-toolname) after the backing server disconnected post-boot — remote endpoint went down, stdio process exited, hypervisor restarted and failed to reconnect, or the server was removed from the JSON while tools were still registered.

Common situations: Long-running chats where a remote MCP server dropped (auth expiry, network change, laptop sleep); local stdio server crashing on bad args; editing mcp_servers.json without re-registering tools; container restarts severing outbound connections.

Related errors

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AI-assisted analysis of Mintplex-Labs/anything-llm@3aec848f28 (2026-08-18). Data as JSON: /api/errors/4a01648d7ec3baaf. Report an issue: GitHub.

Appendix: source

Thrown at server/utils/MCP/index.js:83

            name: `${name}-${tool.name}`,
            setup: (aibitat) => {
              aibitat.function({
                super: aibitat,
                name: `${name}-${tool.name}`,
                controller: new AbortController(),
                description: tool.description,
                isMCPTool: true,
                examples: [],
                parameters: {
                  $schema: "http://json-schema.org/draft-07/schema#",
                  ...tool.inputSchema,
                },
                handler: async function (args = {}) {
                  try {
                    const mcpLayer = new MCPCompatibilityLayer();
                    const currentMcp = mcpLayer.mcps[name];
                    if (!currentMcp)
                      throw new Error(
                        `MCP server ${name} is not currently running`
                      );

                    aibitat.handlerProps.log(
                      `Executing MCP server: ${name}:${tool.name} with args:`,
                      args
                    );
                    aibitat.introspect(
                      `Executing MCP server: ${name} with ${JSON.stringify(args, null, 2)}`
                    );
                    const result = await currentMcp.callTool({
                      name: tool.name,
                      arguments: args,
                    });
                    aibitat.handlerProps.log(
                      `MCP server: ${name}:${tool.name} completed successfully`,
                      result
                    );

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