Cloud Agents: Agent encountered an error after AttachPty — “No environment build used” (repro on Cursor default image)

[jeanbaptistecaplan]

Where does the bug appear (feature/product)?

Cloud Agent (GitHub, Slack, Web, Linear)

Describe the Bug

Hi Cursor team,
This report was drafted by Cursor’s AI coding agent from environment/startup logs I copied out of the Cloud Agents UI. I did not alter the log contents; the chronology below is based on those pasted logs. Please treat the interpretation as secondary to the run IDs and the raw logs you can pull server-side.

Summary

Every Cloud Agent we start ends with Environment error then Agent encountered an error. The VM appears to boot successfully (clone, install, desktop/VNC, exec-daemon, and on default-image runs: tmux session + PTY attach). Failure happens after that, before the model answers. All runs show:

Run IDs

• Run A — multi-repo team env (custom Dockerfile via walter-skills hub): bc-8c2eb701-f0b7-44fb-865e-cf736c288205
• Run B — minimal probe repo walter-learning/walter-agent-hub (no Dockerfile, Cursor default image): bc-d44e71ac-093e-4710-9e33-ddc6da6c8977
• Run C — single repo walter-learning/walter-crm: bc-ac644e60-f88b-4ebf-91c1-dc5a977d5098
  Privacy / tracing in logs: "ghostMode": true, "willInitTracing": false.

What we ruled out

1. Custom Dockerfile / missing packages — same crash on Cursor’s default image.
2. Multi-repo complexity — same crash on the single-repo probe.
3. Heavy install — probe install is smoke-only.
4. D-Bus tweaks in our custom image — default image has working D-Bus and still fails the same way.

Asks

1. Please inspect runs A/B/C server-side and tell us the real failure after AttachPty.
2. What does No environment build used [internal] mean here, and is it related?
3. Any recommended workaround (enable Builds, Personal vs Team environment, Privacy Mode off for one diagnostic run, reconnect GitHub, recreate Environment)?
   Happy to run a Privacy Mode–off diagnostic if that helps log access.
   Thanks.

Jean-Baptiste

Steps to Reproduce

1. Open https://cursor.com/agents (signed in on the Walter Learning team).
2. Start a new Cloud Agent against repo walter-learning/walter-agent-hub (private), branch main.
   • This repo has a minimal .cursor/environment.json with no build.dockerfile (Cursor default Ubuntu image) and a trivial install script that only prints smoke checks.
3. Use a minimal prompt, for example:

   Run uname -a, pwd, and git status --short, then reply PROBE_OK.

4. Do not edit files; wait for environment startup to finish.
5. Observe:
   • UI shows Environment error and No environment build used [internal].
   • Startup logs show clone/install/desktop/VNC/exec-daemon succeeding.
   • On this default-image run, logs also show Created tmux session → Spawning PTY → Attached tmux session → AttachPty.
   • Then the run fails with Agent encountered an error before the model answers.
6. Optional same-failure checks (same symptom):
   • Multi-repo custom Dockerfile env: run bc-8c2eb701-f0b7-44fb-865e-cf736c288205
   • Single-repo walter-crm: run bc-ac644e60-f88b-4ebf-91c1-dc5a977d5098
   • Minimal probe above: run bc-d44e71ac-093e-4710-9e33-ddc6da6c8977

Operating System

MacOS

Version Information

Everything was done through the web dashboard

For AI issues: which model did you use?

Auto (balance)

For AI issues: add Request ID with privacy disabled

• Multi-repo custom Dockerfile env: run bc-8c2eb701-f0b7-44fb-865e-cf736c288205
• Single-repo walter-crm: run bc-ac644e60-f88b-4ebf-91c1-dc5a977d5098
• Minimal probe above: run bc-d44e71ac-093e-4710-9e33-ddc6da6c8977

Does this stop you from using Cursor

Yes - Cursor is unusable

[mohitjain (Mohit)]

Hey there,

What you’re hitting isn’t your Dockerfile, repo, D-Bus, or Privacy Mode. If your team has Impose Auto set to Hard (admins can check this in the team dashboard’s model settings), the environment setup step is running into a mismatch with that setting when it kicks off. This isn’t intended behavior, and we’ve let the team know. It’s an issue we’re tracking.

Workaround to unblock you now:

1. As team admin, temporarily switch Impose Auto to Off (or Soft).
2. Start your Cloud Agent(s) again; environment setup should complete.
3. Re-enable Impose Auto: Hard. Normal Cloud Agent runs on Auto keep working under Hard; this only affects the initial environment setup step.

Also:

• No environment build used [internal] is unrelated status text. It just means the VM booted just-in-time from the default image rather than a prebuilt Environment Build. Not the failure.
• No Privacy Mode-off diagnostic needed; we have enough from the run IDs.

I’ll follow up here when there’s an update.

[marfay (Mark)]

Where does the bug appear (feature/product)?

Cloud Agent (GitHub, Slack, Web, Linear)

Describe the Bug

/env-setup  Set up a new development environment for this codebase. Follow the “Set up a new environment” workflow in the env-setup skill. Run the relevant applications and demonstrate that the environment works end to end.

Steps to Reproduce

Try to provision a new Cloud Agent environment for a repo

Screenshots / Screen Recordings

Operating System

Linux

Version Information

https://cursor.com/agents/bc-4832fa03-321b-4024-9e46-edea1d5906d9?setupSessionId=f7c91803-e494-49be-85cb-445d5bb198db

For AI issues: add Request ID with privacy disabled

Request ID: bc-4832fa03-321b-4024-9e46-edea1d5906d9

Does this stop you from using Cursor

Yes - Cursor is unusable