🚨 Docker Error Guide: 'failed to solve with frontend dockerfile.v0' BuildKit Build Failures

Exact Error Message

BuildKit (the default builder since Docker 23) reports solve failures through the dockerfile.v0 frontend. The exact wording varies with the root cause, but the wrapper line is consistent:

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 > [internal] load build definition from Dockerfile:
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failed to solve with frontend dockerfile.v0: failed to create LLB definition: dockerfile parse error on line 7: unknown instruction: RUNN

You may also see the read-failure and cache-key variants:

failed to solve: failed to read dockerfile: open /var/lib/docker/tmp/buildkit-mount123/Dockerfile: no such file or directory

failed to solve: rpc error: code = Unknown desc = failed to compute cache key: failed to calculate checksum of ref ...: "/app/dist": not found

What It Means

failed to solve is BuildKit’s umbrella error for any failure while turning your Dockerfile into a low-level build (LLB) graph and executing it. The frontend dockerfile.v0 part names the component that parses the Dockerfile. When you see this, BuildKit either could not parse the Dockerfile into a definition (failed to create LLB definition), could not find the Dockerfile to read (failed to read dockerfile), or could not resolve a step while solving the graph (failed to compute cache key, failed to resolve source metadata). The error halts the build before or during step execution, so no image is produced.

Common Causes

• Dockerfile syntax errors — a misspelled instruction (RUNN), an unclosed heredoc, or a malformed FROM ... AS line fails the parse stage.
• Missing Dockerfile or wrong -f path — failed to read dockerfile means the path passed to -f (or the implicit ./Dockerfile) does not exist in the build context.
• Unresolved build ARG or base image — a FROM ${BASE} with no --build-arg BASE=... default leaves the base image empty, or the referenced tag does not exist.
• BuildKit-specific syntax not enabled — features like RUN --mount=type=cache require a # syntax=docker/dockerfile:1 directive or a recent frontend; older frontends reject them.
• Secret or SSH mount not provided — RUN --mount=type=secret,id=npmrc fails to solve if the build is invoked without --secret id=npmrc,....
• Network failure during FROM — BuildKit cannot pull the base image metadata (failed to resolve source metadata).
• Frontend version mismatch — a # syntax= pin to a frontend image that cannot be pulled, or one too old for the syntax used.

How to Reproduce the Error

A typo in an instruction reproduces the parse failure deterministically:

# Dockerfile
FROM alpine:3.20
RUNN echo "hello"

docker build -t solve-demo .

failed to solve with frontend dockerfile.v0: failed to create LLB definition: dockerfile parse error on line 2: unknown instruction: RUNN

Pointing -f at a path that does not exist reproduces the read failure:

docker build -f docker/Dockerfile.prod -t solve-demo .

failed to solve: failed to read dockerfile: open .../Dockerfile.prod: no such file or directory

Diagnostic Commands

Re-run with plain progress so BuildKit prints the full, untruncated step output and the exact failing line:

docker build --progress=plain --no-cache -t solve-demo . 2>&1 | tail -40

Confirm BuildKit is the active builder and inspect its version:

DOCKER_BUILDKIT=1 docker build -t solve-demo .
docker buildx version
docker buildx inspect --bootstrap | grep -i 'driver\|buildkit'

Verify the Dockerfile path and the build context actually contain what you expect:

ls -la ./Dockerfile docker/Dockerfile.prod
docker buildx build --print . 2>/dev/null   # dry-run the LLB definition

Check the # syntax= directive and base image reference at the top of the file:

head -5 Dockerfile
docker manifest inspect alpine:3.20 >/dev/null && echo "base reachable" || echo "FROM unreachable"

Step-by-Step Resolution

1. Fix Dockerfile syntax. Read the dockerfile parse error on line N from --progress=plain and correct the instruction. RUNN becomes RUN; an unterminated <<EOF heredoc needs its closing delimiter; FROM x AS must name a stage.

2. Correct the Dockerfile path. If you see failed to read dockerfile, the -f path is wrong or the file is excluded from the context. Pass the real path and ensure the context (. argument) is the directory that contains it:

docker build -f docker/Dockerfile.prod -t app docker/

3. Supply build ARGs and valid base images. Give ARG a default or pass --build-arg, and confirm the base tag exists:

ARG BASE=node:20-bookworm
FROM ${BASE}

docker build --build-arg BASE=node:20-bookworm -t app .

4. Enable BuildKit syntax features. Add the syntax directive as the first line so cache mounts, secrets, and COPY --link parse:

# syntax=docker/dockerfile:1
FROM golang:1.22 AS build
RUN --mount=type=cache,target=/root/.cache/go-build go build ./...

5. Provide secret and SSH mounts. A RUN --mount=type=secret,id=npmrc requires the secret on the command line:

docker build --secret id=npmrc,src=$HOME/.npmrc -t app .

6. Resolve network failures on FROM. If solving fails on base-image metadata, log in to the registry, check connectivity, and retry:

docker login registry.example.com
docker pull alpine:3.20

7. Pin or update the frontend. If a # syntax= image cannot be pulled, pin to a known-good version (docker/dockerfile:1.7) and ensure the daemon can reach Docker Hub.

How to Prevent the Issue

• Lint Dockerfiles in CI with hadolint or docker buildx build --check so syntax errors fail fast before merge.
• Pin the frontend with # syntax=docker/dockerfile:1 to get stable, well-documented parsing behaviour across machines.
• Give every ARG used in FROM a sane default and reference base images by an explicit, existing tag (or digest).
• Keep secrets out of layers — use --mount=type=secret and document the required --secret flags in your build script or Makefile.
• Standardise the build invocation (a make build target) so the -f path and context are never guessed.

Related Docker Errors

• COPY failed: file not found in build context — the most common follow-on once the Dockerfile parses; see the COPY failed file not found guide.
• failed to compute cache key: ... not found — a COPY/ADD source missing from the context, covered in the same guide.
• no space left on device during a build — the builder cache fills the disk mid-solve. See the no space left on device guide.
• More build and runtime fixes in the Docker guides.