Cowork: scheduled-task prompt cannot be updated — even a single-paragraph prompt is rejected ("path traversal detected" / "failed to update")

Status Open

Maintainer reply None cached

Activity 3 comments · opened Aug 16, 2026

Product

Claude Cowork (desktop app, macOS) — a scheduled task that runs remotely in the cloud.

Summary

An existing daily scheduled task runs fine on schedule, but its prompt body cannot be updated through any route. The update is rejected regardless of content or length.

Observed behavior

Updating via the update_scheduled_task tool fails with: Invalid file path: path traversal detected.
Updating by pasting a new prompt into the scheduled-task editor UI fails with: failed to update.
A no-op update (e.g. toggling enabled: true, no prompt change) succeeds — so the task's stored config is valid.
Pasting even a single short paragraph as the new prompt is still rejected — so it is not the prompt's size, nor any specific path/content.

Impact

The task is frozen at its current prompt — no edits can ship. It keeps running daily, so only prompt updates are blocked.

Notes

The prompt legitimately contains absolute file paths (/Users/<user>/…) and ellipses (...), which may be tripping an over-aggressive path-traversal content filter — but since even a plain one-paragraph prompt is rejected, the update mechanism itself appears broken, not just a content filter.
Environment: Cowork desktop app, macOS.

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3 Comments

agentneo16 · 14 days ago

Update / additional diagnostic: **creating a new scheduled task with the exact same prompt content succeeds (it saves and runs in the cloud), while updating an existing task's prompt with that same content is rejected ("path traversal detected" from the tool, "failed to update" in the UI). So the bug appears isolated to the update path (update_scheduled_task / the UI's edit-save on an existing task) — the create path accepts prompts that update rejects**. This narrows it to the update endpoint's validation, not the prompt content itself.

agentneo16 · 14 days ago

Clarification + more evidence: the create success I mentioned earlier was a cloud task. Local scheduled-task creation ('Run on your computer' enabled) fails — for a trivial one-line-instruction task in a plain non-git folder, and for a full real prompt alike — with 'Failed to create scheduled task. You can try again.' So the state is: cloud-create works, but local-create AND update both fail, independent of prompt content, size, or folder. Env: macOS 26.6.1, Claude desktop app 1.30096.5.

drksecretmc · 6 days ago

Confirming this on Windows too — same failure mode, matches the second update exactly.

Platform: Windows 11, Claude desktop app 1.34493.1.0

create_scheduled_task (local) and update_scheduled_task both fail with Invalid file path: path traversal detected (server-side log tag [ScheduledTasksMcpServer]).
100% reproducible since at least 2026-08-24, across multiple taskIds, empty vs. real prompts, cronExpression and fireAt alike.
list_scheduled_tasks works fine.
Independent of prompt content/size and independent of local folder/drive configuration — ruled out a local Documents-folder redirect on this machine as a contributing cause before landing here.
Stack trace bottoms out in minified app code (app.asar/.vite/build/index.chunk-*.js, functions RRn/LRn) with no path echoed, so the actual value tripping the check isn't visible client-side.

So: local create + update both broken on Windows too, same generic error, matches the "local-create AND update both fail, independent of content" finding above.