# Troubleshooting

* [Cannot push to a registry](#cannot-push-to-a-registry)
  * [BuildKit container logs](#buildkit-container-logs)
  * [With containerd](#with-containerd)
* [`repository name must be lowercase`](#repository-name-must-be-lowercase)

## Cannot push to a registry

While pushing to a registry, you may encounter these kinds of issues:

* `failed commit on ref "layer-sha256:...": invalid content digest in response: invalid checksum digest format`
* `failed commit on ref "layer-sha256:...": no response`
* `failed commit on ref "manifest-sha256:...": unexpected status: 400 Bad Request`
* `failed commit on ref "manifest-sha256:...": unexpected status: 401 Unauthorized`
* `unexpected response: 401 Unauthorized`

These issues are not directly related to this action but are rather linked to
[Buildx](https://github.com/docker/buildx), [BuildKit](https://github.com/moby/buildkit),
[containerd](https://github.com/containerd/containerd) or the registry on which
you're pushing your image. The quality of error message depends on the registry
and are usually not very informative.

### BuildKit container logs

To help you solve this, you have to [enable debugging in the setup-buildx](https://github.com/docker/setup-buildx-action#buildkit-container-logs)
action step and attach BuildKit container logs to your issue.

### With containerd

Next you can test pushing with [containerd action](https://github.com/crazy-max/ghaction-setup-containerd)
using the following workflow. If it works then open an issue on [BuildKit](https://github.com/moby/buildkit)
repository.

```yaml
name: containerd

on:
  push:

jobs:
  containerd:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v4
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v3
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3
        with:
          buildkitd-flags: --debug
      -
        name: Set up containerd
        uses: crazy-max/ghaction-setup-containerd@v2
      -
        name: Build Docker image
        uses: docker/build-push-action@v6
        with:
          context: .
          platforms: linux/amd64,linux/arm64
          tags: docker.io/user/app:latest
          outputs: type=oci,dest=/tmp/image.tar
      -
        name: Import image in containerd
        run: |
          sudo ctr i import --base-name docker.io/user/app --digests --all-platforms /tmp/image.tar
      -
        name: Push image with containerd
        run: |
          sudo ctr --debug i push --user "${{ secrets.DOCKER_USERNAME }}:${{ secrets.DOCKER_PASSWORD }}" docker.io/user/app:latest
```

## `repository name must be lowercase`

You may encounter this issue if you're using `github.repository` as a repo slug
in your tag:

```
#6 exporting to image
#6 exporting layers
#6 exporting layers 1.2s done
#6 exporting manifest sha256:b47f7dfb97b89ccd5de553af3c8cd94c4795884cbe5693e93946b1d95a7b1d12 0.0s done
#6 exporting config sha256:995e93fab8196893192f08a38deea6769dc4d98f86cf705eccc24ec96a3e271c 0.0s done
#6 ERROR: invalid reference format: repository name must be lowercase
------
 > exporting to image:
------
error: failed to solve: invalid reference format: repository name must be lowercase
```

or a cache reference:

```
#10 importing cache manifest from ghcr.io/My-Org/repo:main
#10 ERROR: invalid reference format: repository name must be lowercase
```

To fix this issue you can use our [metadata action](https://github.com/docker/metadata-action)
to generate sanitized tags:

```yaml
- name: Docker meta
  id: meta
  uses: docker/metadata-action@v4
  with:
    images: ghcr.io/${{ github.repository }}
    tags: latest

- name: Build and push
  uses: docker/build-push-action@v6
  with:
    context: .
    push: true
    tags: ${{ steps.meta.outputs.tags }}
```

Or a dedicated step to sanitize the slug:

```yaml
- name: Sanitize repo slug
  uses: actions/github-script@v6
  id: repo_slug
  with:
    result-encoding: string
    script: return 'ghcr.io/${{ github.repository }}'.toLowerCase()

- name: Build and push
  uses: docker/build-push-action@v6
  with:
    context: .
    push: true
    tags: ${{ steps.repo_slug.outputs.result }}:latest
```