openai/codex · error · anyhow::Error
MCP server '{server}' is not connected
Error message
MCP server '{server}' is not connected What it means
Error "MCP server '{server}' is not connected" thrown in openai/codex.
Source
Thrown at codex-rs/codex-mcp/src/connection_manager.rs:905
view.metadata.environment_id
);
}
if !view.tool_filter.allows(tool) {
return Err(anyhow!(
"tool '{tool}' is disabled for MCP server '{server}'"
));
}
let client = if wait_for_server {
view.connection
.client()
.await
.context("failed to get client")?
} else {
let client = view
.connection
.client
.ready_client()
.ok_or_else(|| anyhow!("MCP server '{server}' is not connected"))?;
if client.client.is_closed().await {
bail!("MCP server '{server}' is not connected");
}
client
};
let effective_timeout = match (view.tool_timeout, requested_timeout) {
(Some(server_timeout), Some(requested_timeout)) => {
Some(server_timeout.min(requested_timeout))
}
(server_timeout, requested_timeout) => server_timeout.or(requested_timeout),
};
let result: rmcp::model::CallToolResult = client
.client
.call_tool(tool.to_string(), arguments, meta, effective_timeout)
.await
.with_context(|| format!("tool call failed for `{server}/{tool}`"))?;
View on GitHub (pinned to 339751715c)
Solutions
- Check that MCP server '{server}' is configured and its startup succeeded; inspect its startup logs and retry the connection.
When it happens
Trigger: Thrown at codex-rs/codex-mcp/src/connection_manager.rs:905 when the library encounters an invalid state.
Common situations: See trigger scenarios.
AI-assisted analysis of openai/codex@339751715c (2026-08-25).
Data as JSON: /api/errors/614a3cf67cf37402.
Report an issue: GitHub.