What causes "could not find the file %s in container %s" in docker/compose?

Check the source path spelling and that it exists in the real container (`docker compose exec ls `)

could not find the file %s in container %s

Error message

could not find the file %s in container %s

What it means

Dry-run mode (`docker compose --dry-run`) simulates API calls. `CopyFromContainer` first stats the source path via `ContainerStatPath`; if the stat fails, it reports the file as not found in the container. Since dry-run containers are simulated, this usually reflects a path that does not exist on the host or a simulated container that was never created.

Source

Thrown at pkg/dryrun/dryrunclient.go:192

func (d *DryRunClient) ContainerRestart(ctx context.Context, container string, options client.ContainerRestartOptions) (client.ContainerRestartResult, error) {
	return client.ContainerRestartResult{}, nil
}

func (d *DryRunClient) ContainerStart(ctx context.Context, container string, options client.ContainerStartOptions) (client.ContainerStartResult, error) {
	return client.ContainerStartResult{}, nil
}

func (d *DryRunClient) ContainerStop(ctx context.Context, container string, options client.ContainerStopOptions) (client.ContainerStopResult, error) {
	return client.ContainerStopResult{}, nil
}

func (d *DryRunClient) ContainerUnpause(ctx context.Context, container string, options client.ContainerUnpauseOptions) (client.ContainerUnpauseResult, error) {
	return client.ContainerUnpauseResult{}, nil
}

func (d *DryRunClient) CopyFromContainer(ctx context.Context, container string, options client.CopyFromContainerOptions) (client.CopyFromContainerResult, error) {
	if _, err := d.ContainerStatPath(ctx, container, client.ContainerStatPathOptions{Path: options.SourcePath}); err != nil {
		return client.CopyFromContainerResult{}, fmt.Errorf("could not find the file %s in container %s", options.SourcePath, container)
	}
	return client.CopyFromContainerResult{
		Content: io.NopCloser(bytes.NewReader(nil)),
	}, nil
}

func (d *DryRunClient) CopyToContainer(ctx context.Context, container string, options client.CopyToContainerOptions) (client.CopyToContainerResult, error) {
	return client.CopyToContainerResult{}, nil
}

func (d *DryRunClient) ImageBuild(ctx context.Context, reader io.Reader, options client.ImageBuildOptions) (client.ImageBuildResult, error) {
	return client.ImageBuildResult{
		Body: io.NopCloser(bytes.NewReader(nil)),
	}, nil
}

func (d *DryRunClient) ImageInspect(ctx context.Context, imageName string, options ...client.ImageInspectOption) (client.ImageInspectResult, error) {
	caller := getCallingFunction()

View on GitHub (pinned to ddc4b044b6)

Solutions

Check the source path spelling and that it exists in the real container (`docker compose exec <svc> ls <path>`)
Run the copy command without `--dry-run` — dry-run cannot verify file contents in a container that isn't there

Defensive patterns

Strategy: validation

Validate before calling

# verify the path exists in the real container before dry-running a copy
docker compose exec <service> test -f /path/to/file && docker compose --dry-run cp <service>:/path/to/file ./dest

Prevention

Treat --dry-run output as a plan, not a filesystem validation
Check source paths with `docker compose exec ... test -f` in scripts that later copy for real

When it happens

Trigger: A command run with `--dry-run` that copies files out of a container (e.g. `docker compose --dry-run cp <svc>:<path> ./dest`) where the stat of `options.SourcePath` fails in the simulated client.

Common situations: Using `compose cp` in dry-run with a typo'd source path; dry-running a workflow where the container doesn't actually exist; expecting dry-run to validate real container contents it cannot see.

Related errors

AI-assisted analysis of docker/compose@ddc4b044b6 (2026-08-15). Data as JSON: /api/errors/d00b41ef5f432a92. Report an issue: GitHub.