macOS: lingering-process check flags another user's Docker Desktop, start fails #842

Bug report

Description

On a Mac with two macOS user accounts, Docker Desktop cannot start in one account while it is running in the other. At startup, the lingering-processes check lists the other account's Docker Desktop process as a lingering process of the current account. It tries to kill it and gets operation not permitted, because the process belongs to another user. It then shows the "Lingering processes detected" dialog, and the backend exits with status 151.

The check does not appear to filter the processes it lists by the current user. The dialog's offer to stop the listed process cannot succeed from the second account. If it did succeed, it would stop another user's Docker Desktop.

docker/for-mac#2916 (2018, "com.docker.supervisor failed to start when Docker running in another account") was closed with a dedicated error message for this situation. With the lingering-processes check, the second account now gets the generic lingering-process dialog instead.

Steps to reproduce

1. On one Mac, have two user accounts, A and B, both able to run the single Docker Desktop install in /Applications.
2. Log in as A and start Docker Desktop. Leave it running, and leave A logged in.
3. Log in as B (for example with Fast User Switching) and start Docker Desktop.

Expected behavior

Docker Desktop in B either starts, or reports that Docker Desktop is already running in another user account, without offering to stop that account's processes.

Actual behavior

B gets the "Lingering processes detected" dialog listing A's Docker Desktop PID, and B's Docker Desktop exits.

ps -axo user,pid,ppid,comm in B shows PID 12538 owned by account A: /Applications/Docker.app/Contents/MacOS/Docker Desktop.app/Contents/MacOS/Docker Desktop, with parent 12497, A's com.docker.backend.

B's ~/Library/Containers/com.docker.docker/Data/log/host/com.docker.backend.log:

[2026-11-11T09:34:39.568508000Z][com.docker.backend.lingering-processes] found lingering process: pid=12538 ppid=12497 name=Docker Desktop
[2026-11-11T09:34:39.568617000Z][com.docker.backend.lingering-processes] silently killing lingering process with pid 12538 (Docker Desktop)
[2026-11-11T09:34:39.568699000Z][com.docker.backend.lingering-processes][W] operation not permitted
[2026-11-11T09:34:39.624841000Z][com.docker.backend.lingering-processes] found lingering process: pid=12538 ppid=12497 name=Docker Desktop
[2026-11-11T09:34:39.625025000Z][com.docker.backend.report] reporting error to user: lingering processes detected at startup (processCount: 1, processDetails: * pid 12538: Docker Desktop
[2026-11-11T09:34:45.091391000Z][com.docker.backend.report] error dialog exited: process 34526 exited with signal code 9 and WaitStatus 9
[2026-11-11T09:34:45.610593000Z][com.docker.backend] monitor exited: exit status 151

Workaround

Quit Docker Desktop in the other account first, or use another container runtime in the second account.

Platform

macOS

Version information

• Docker Desktop 4.98.0 (245422), one install in /Applications, used from two macOS user accounts
• Docker CLI bundled with Docker Desktop: 29.9.2, API 1.56
• macOS 27.0.1 (26A434), Apple silicon (arm64)
• docker version from account B reaches no engine, because B's Docker Desktop does not start

Diagnostics ID

Not uploaded. Docker Desktop does not start in the affected account, so the in-app diagnostics upload is not available there. One can be added on request.