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Codex App: new task creation times out when configured MCP server is unreachable #31359
Description
What version of the Codex App are you using (From “About Codex” dialog)?
26.623.141536
What subscription do you have?
ChatGPT Pro
What platform is your computer?
Darwin 25.5.0 arm64 arm
What issue are you seeing?
Immediately after updating Codex Desktop to version 26.623.141536, I could no longer create new chats.
Every attempt failed with:
- Task creation failed — Timeout
- Chat startup failed — Timeout
Existing chats continued to work normally.
After investigating, I found that the issue was caused by an MCP server configured with a LAN-only endpoint.
When working outside my local network, that MCP server became unreachable. As a result, Codex waited for the MCP connection and eventually timed out, preventing any new task from being created.
After replacing the LAN-only MCP endpoint with a reachable Tailscale MagicDNS endpoint and restarting Codex, new chats worked immediately.
Expected behavior:
If an MCP server is unreachable, Codex should mark that MCP as unavailable, display a warning if necessary, and continue creating the task.
Actual behavior:
A single unreachable MCP server prevents all new task creation until timeout.
This behavior appears to have started after updating to version 26.623.141536.
What steps can reproduce the bug?
Feedback ID: no-active-thread-019f3add-322f-7703-b72a-f7c57de75730
What is the expected behavior?
If an MCP server is unreachable, Codex should mark that MCP as unavailable and continue creating the task instead of failing with a timeout.
Additional information
Feedback ID: no-active-thread-019f3add-322f-7703-b72a-f7c57de75730
The issue was resolved by replacing the LAN-only MCP endpoint with a reachable Tailscale MagicDNS endpoint.
This suggests that Codex currently blocks new task creation while waiting for an unreachable MCP server instead of treating it as unavailable.
Activity
github-actions commentedon Jul 7, 2026
Potential duplicates detected. Please review them and close your issue if it is a duplicate.
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josheverett commentedon Jul 11, 2026
Confirmed the same failure class on macOS, with a configured MCP server that was not fully unreachable but was instead backed by a live, unhealthy local process.
A Codex agent had added the local HTTP MCP endpoint as a persistent global entry in
~/.codex/config.tomlafter being instructed to use it. The user did not realize the agent had made that configuration durable.Measured behavior while broken:
thread/starttimed out after exactly 30 seconds.mcpServerStatus/listtook about 65.1 seconds.Terminating the unhealthy server immediately restored conversation creation. Removing the persistent MCP entry and relaunching made the fix durable;
codex mcp list --jsonthen completed in about 4.6 seconds and no furtherthread/starttimeouts appeared.This shows that the problem is broader than a completely unreachable endpoint: a half-alive or stalled optional MCP server can also block all new task creation.
The failure began around an app update, but no causal role for the update was established.
Disclosure: this comment was drafted and posted by ChatGPT on the user's behalf from diagnostics the user reviewed and approved.
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