Cloud session create times out waiting for remote sandbox CLI host

[fabianluque]

Short summary

Cloud session creation fails every time with RPC -32603: timed out waiting for the remote sandbox CLI host to connect.

Affected version or release

GitHub Copilot app 1.1.12 on macOS 26.6.2 (25G83)

Installation context

GitHub Copilot desktop app. Creating a Cloud session against the private repository Apex-Global-Solutions/ARWorkflow (default branch master). Local/worktree sessions for the same repo work.

The original reporter uses Enterprise Managed User FLuque_axg (cannot file on this public repo). Filed from personal account fabianluque.

What happened?

Every attempt to create a new Cloud session fails at approximately the 67-second mark. The client reports that the cloud session was created, but the remote CLI host never connects in time.

Error shown in the app:

Session creation failed
Failed to create session: RPC error -32603: Request session.create failed with message: Timed out waiting for the remote sandbox to start. The cloud session was created but its CLI host did not connect in time. Please try again.

This is 100% reproducible (every attempt).

Steps to reproduce

1. Open the GitHub Copilot app (1.1.12) on macOS.
2. Create a new Cloud session targeting Apex-Global-Solutions/ARWorkflow.
3. Wait for session creation.

Expected behavior

The cloud session starts and the remote CLI host connects so the session becomes usable.

Additional context

• Timing is consistent: the error appears around 67 seconds after starting creation.
• The remote session appears to be created; only the CLI host connection times out.
• Local / worktree sessions continue to work for the same repository.
• Repo includes .github/workflows/copilot-setup-steps.yml (sets up .NET from global.json and Node.js 20.19).
• GitHub-reported repository size is ~49 MB.
• This is a different failure from an earlier Failed to create remote session in the cloud: 502 (GitHub Unicorn HTML page) seen on 2026-08-17 during a GitHub outage.

[Falkicon]

Reproduced on August 27, 2026 on Windows with GitHub Copilot App 1.0.80, using an Enterprise Managed User and a private repository.

The failure text matches this issue exactly:

Timed out waiting for the remote sandbox to start. The cloud session was created but its CLI host did not connect in time.

Additional observations:

• The App persisted a cloud session record and created the corresponding GitHub Agent Task.
• Both the task and its session remained queued, with no base or head ref assigned, after the App timed out.
• Local/worktree sessions for the repository work normally.
• Repository provisioning is healthy: independent cloud sessions started through GitHub Agents / the Agent Tasks REST API on the same repository and default branch complete successfully, including the repository setup workflow.
• Previous App-created attempts produced the same orphaned queued state.

This appears to be an App-to-remote-CLI-host connection/handshake failure rather than a repository setup or GitHub-hosted runner failure.

[saalse]

I am also experiencing this exact issue.

When attempting to create a Copilot cloud session, the creation process consistently times out with the following error:

Failed to create session: RPC error -32603: Request session.create failed with message: Timed out waiting for the remote sandbox to start. The cloud session was created but its CLI host did not connect in time. Please try again.

Additional context from my troubleshooting:

• This is happening consistently.
• Local (worktree) sessions for the same repository work perfectly fine.
• Added a .github/workflows/copilot-setup-steps.yml workflow and disabled the Copilot cloud agent firewall, but the issue persists.
• The copilot-setup-steps.yml workflow is not even triggered during the failed creation attempts, indicating the failure happens early in the provisioning/connection phase before the repo is even checked out.