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Codex Desktop macOS crash/blank threads when remote feature flag enables unknown thread_tools feature #26850
Description
Summary
Codex Desktop on macOS repeatedly crashes with (code=null, signal=SIGKILL) and then reopens with thread titles visible in the sidebar but the selected thread body blank. Local session JSONL files are still present and contain messages, so this looks like an app-server crash during thread read/resume rather than lost chat data.
Environment
- Codex Desktop app:
26.602.40724(CFBundleVersion3593) - Install path:
/Applications/Codex.app - macOS:
26.1(25B78) - Launch method: Dock, bundle id
com.openai.codex - CLI/runtime check:
codex features listdoes not listthread_tools
Relevant codex features list excerpt:
apps stable true
apps_mcp_path_override under development false
enable_mcp_apps under development false
plugins stable true
workspace_owner_usage_nudge removed false
Crash signature
Crash screen shows:
(code=null, signal=SIGKILL)
Most recent error: {"timestamp":"2026-06-07T04:32:30.293649Z","level":"WARN","fields":{"message":"unknown feature key in config: thread_tools"},"target":"codex_features"}
App logs show the desktop feature list enabling thread_tools shortly before the app-server closes:
Features enabled enabledFeatures="enable_request_compression, collaboration_modes, personality, request_rule, image_generation, image_detail_original, workspace_dependencies, guardian_approval, apply_patch_streaming_events, workspace_owner_usage_nudge, thread_tools, enable_mcp_apps, apps, plugins, tool_call_mcp_elicitation"
app_server_connection.closed ... reason={"timestamp":"2026-06-07T04:32:30.293649Z","level":"WARN","fields":{"message":"unknown feature key in config: thread_tools"},"target":"codex_features"} signal=SIGKILL
After the app-server crash, thread read/resume calls fail, which matches the blank chat pane:
Request failed ... method=thread/read ... "Codex app-server is not available"
Request failed ... method=thread/resume ... "Codex app-server is not available"
Local config check
~/.codex/config.toml was checked and does not contain thread_tools. Adding it manually was not attempted because unknown feature keys appear to be the crash trigger. The only local [features] entry present was unrelated.
Reproduction observed
- Open Codex Desktop from the Dock.
- Select an existing project thread.
- Sidebar thread titles load, but the chat body is blank.
- In some attempts, Codex shows the SIGKILL crash page with the
unknown feature key in config: thread_toolswarning. - Reloading/reopening may temporarily show the sidebar again, but thread bodies remain blank or crash on read/resume.
Expected behavior
Codex should ignore or safely handle an unknown remotely-enabled feature flag, or the app-server/runtime bundled with the desktop app should understand thread_tools. Existing local sessions should remain readable.
Actual behavior
A remotely-enabled thread_tools feature appears to be passed to a runtime that does not recognize it, causing the app-server to terminate and leaving existing threads unreadable in the UI.
Data safety note
Local session JSONL files were verified to still exist and contain the expected message counts. This appears to be a UI/app-server crash, not deletion of chat history.
Reported on behalf of a user from a live Codex Desktop troubleshooting session; private project names, home paths, thread IDs, and screenshots intentionally omitted.
Activity
shahrul91 commentedon Jun 8, 2026
Additional crash observed on the same installation on 2026-06-08.
This one is a different immediate error from the original
thread_toolsfeature-key crash, but it still terminates the app-server with(code=null, signal=SIGKILL)and shows the desktop crash screen.New crash signature from the UI/logs:
Relevant versions on this same machine:
This looks like another version/capability mismatch: the app/server attempts MCP
resources/listandresources/templates/listagainst MCP servers that do not implement those methods. The app-server treats the warnings as the fatal SIGKILL reason surfaced to the user.ingmaras commentedon Jun 20, 2026
Same
thread_toolscrash happening on Codex Desktop 26.616.41845 on macOS Tahoe 26.5 (25F71)fugamante commentedon Sep 19, 2026
Confirming that the same frontend/runtime mismatch still reproduces on a current macOS desktop build, although in this case it produces a persistent configuration warning rather than a crash or blank task.
Environment:
Observed warning in Settings > Configuration:
The warning persists after fully quitting and reopening the app. It also persisted across an automatic desktop update from 26.915.31029 to 26.915.31945.
The user and project config files do not contain thread_tools. The related user feature setting is the currently supported multi_agent = true. Read-only inspection of the installed desktop bundle shows that the frontend still references defaultFeatureOverrides.thread_tools, while the bundled core feature registry contains multi_agent and does not recognize thread_tools.
Expected: the desktop frontend should send the supported feature key or omit the retired key.
Actual: the frontend supplies features.thread_tools as a session flag, the bundled core ignores it, and the Configuration panel repeatedly displays a warning.
Current impact on this installation appears cosmetic; no crash, unreadable task, or task-data loss has been observed.