Cloud Agent Docker build fails during setup even with minimal Dockerfile

[snb]

Where does the bug appear (feature/product)?

Background Agent (GitHub, Slack, Web, Linear)

Describe the Bug

Cloud Agent fails during setup at the Docker build step.
Even with a minimal Dockerfile (FROM ubuntu:24.04), the build fails with exit code 1.
No detailed Docker build logs are shown, and the agent never becomes usable.
As a result, no commands (e.g. echo hello) can be executed.

Steps to Reproduce

1. Create a new Cloud Agent for a repository
2. Use the following minimal configuration:

.cursor/environment.json:
{
“build”: {
“context”: “.”,
“dockerfile”: “.cursor/Dockerfile”
}
}

.cursor/Dockerfile:
FROM ubuntu:24.04

3. Start setup

4. Setup reaches “Setting up environment”

5. Then fails with:
   “Docker image build errored (exit code: 1)”

6. Agent never becomes usable and cannot run any commands

Expected Behavior

• Docker build should succeed with a minimal Dockerfile
• Setup should complete successfully
• Agent should be able to run basic commands like echo hello

Screenshots / Screen Recordings

Operating System

MacOS

Version Information

Cursor IDE: 3.2.16
This issue occurs in Cloud Agent (Background Agent), not local IDE.

Additional Information

• This issue has persisted for several days
• It occurs even without any install commands, secrets, or environment variables
• It is reproducible with a completely minimal Dockerfile
• Previously reported related issue:
  Cloud Agent fails to start (501 on save)

This seems to be a backend / infrastructure issue rather than repository configuration.

This issue blocks using Cloud Agent for team workflows.

Does this stop you from using Cursor

Yes - Cursor is unusable

[mohitjain (Mohit)]

I see you reported a similar Cloud Agent issue previously, and I’m sorry you’re running into more trouble. Your Dockerfile and environment.json are correct — this is a server-side infrastructure issue, not anything on your side.

Our team is aware of Docker build failures affecting Cloud Agent setup and is actively working on improvements to the build pipeline. There have been recent infrastructure changes rolling out that should help stabilize this.

Could you try setting up the agent again? If it still fails, please share the Cloud Agent session URL from your browser’s address bar (it looks like cursor.com/agents/bc-``...). That will let me trace the specific failure in our backend logs.

[Colin]

Hey @snb !

The team has made a number of infrastructure improvements to the Cloud Agent Docker build pipeline over the past couple of weeks that should address the build failures you were seeing. Could you try setting up a Cloud Agent again and let me know if it works?