docker/build-push-action "failed to solve" - Buildx not set up

build-push-action drives a buildx builder. Without a prior docker/setup-buildx-action step there is no buildkit instance to solve the build graph, so the build fails.

What this error means

The build-push step fails with "failed to solve" or complains the buildx builder is missing.

github-actions

ERROR: failed to solve: failed to read dockerfile: buildx builder not initialized
##[error]buildx call failed with: ERROR: failed to solve

Common causes

Missing setup-buildx step

No docker/setup-buildx-action ran, so build-push has no builder to use.

Builder failed to initialize

setup-buildx ran but the driver could not start, leaving no usable builder.

How to fix it

Add setup-buildx before build-push

Insert a docker/setup-buildx-action step before the build.
Optionally add setup-qemu for multi-arch.
Re-run; build-push uses the initialized builder.

.github/workflows/docker.yml

- uses: docker/setup-buildx-action@v3
- uses: docker/build-push-action@v6
  with:
    push: true
    tags: ghcr.io/${{ github.repository }}:latest

How to prevent it

Always run setup-buildx-action before build-push-action.
Check the builder startup logs when the solve step fails immediately.

Related guides

docker/build-push-action "tag is needed when pushing to registry" (tags empty)Fix docker/build-push-action failing because the tags input is empty while push is true. GitHub Actions docker/setup-buildx-action "failed to initialize builder"Fix docker/setup-buildx-action "failed to initialize builder" - buildx could not create the builder instance,… GitHub Actions docker/setup-buildx-action Fails to Create the BuilderFix docker/setup-buildx-action failing to bootstrap a builder - a missing QEMU step for cross-arch, an unavai…