What causes "failed to attach to container: %w" in nektos/act?

Check the wrapped Docker error; the container may have exited before attach completed.

failed to attach to container: %w

Error message

failed to attach to container: %w

What it means

Error "failed to attach to container: %w" thrown in nektos/act.

Source

Thrown at pkg/container/docker_run.go:851

out, err := cr.cli.ContainerAttach(ctx, cr.id, client.ContainerAttachOptions{
	Stream: true,
	Stdout: true,
	Stderr: true,
})
if err != nil {
	return fmt.Errorf("failed to attach to container: %w", err)
}

View on GitHub (pinned to 4f41128141)

Solutions

Check the wrapped Docker error; the container may have exited before attach completed.
Ensure the container is created and the Docker daemon connection is stable.

When it happens

Trigger: Thrown at pkg/container/docker_run.go:851 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of nektos/act@4f41128141 (2026-08-15). Data as JSON: /api/errors/e1fa25a16aec9b3f. Report an issue: GitHub.