ERROR

How to Fix Docker Build Failed to Solve Process

Quick Fix Summary

TL;DR

Run `docker builder prune -a` to clear the BuildKit cache and rebuild.

This error occurs when Docker's BuildKit engine fails to parse or execute a step in your Dockerfile. It typically indicates a syntax issue, an unresolvable dependency, or a corrupted build cache.

Diagnosis & Causes

  • Invalid or malformed Dockerfile syntax.
  • Unavailable base image or dependency in registry.
  • Corrupted or incompatible BuildKit cache.
  • Network timeout during image layer fetch.
  • Insufficient disk space for build context.

    • Recovery Steps

    1

    Step 1: Clear the BuildKit Cache

    A corrupted cache is the most common culprit. Prune all builder cache to force a clean build.

    bash 
    docker builder prune -a
# Optional: Also prune the general Docker system
docker system prune -a --volumes
    2

    Step 2: Validate Dockerfile Syntax

    Run a syntax check on your Dockerfile. Ensure all instructions are correct and multi-stage build targets exist.

    bash 
    # Use hadolint for advanced linting (install via package manager)
hadolint Dockerfile
# Or use docker build's dry-run with BuildKit
DOCKER_BUILDKIT=1 docker build --no-cache --progress=plain --target=<your-target> .
    3

    Step 3: Check Network and Registry Accessibility

    Verify you can pull the base image manually. Network proxies or registry auth can cause silent failures.

    bash 
    docker pull <your-base-image>:<tag>
# Check Docker daemon logs for network errors
sudo journalctl -u docker.service | tail -50
    4

    Step 4: Rebuild with Detailed Logging

    Enable BuildKit's plain-text progress output to see the exact step where the solve process fails.

    bash 
    DOCKER_BUILDKIT=1 docker build --no-cache --progress=plain -t your-image:latest .
    5

    Step 5: Disable BuildKit (Fallback)

    If the issue is BuildKit-specific, temporarily revert to the legacy builder to isolate the problem.

    bash 
    export DOCKER_BUILDKIT=0
export COMPOSE_DOCKER_CLI_BUILD=0
docker build --no-cache -t your-image:latest .
    6

    Step 6: Inspect Disk Space and Inodes

    BuildKit requires significant temporary space. Exhaustion can cause cryptic solve failures.

    bash 
    df -h /var/lib/docker/
df -i /var/lib/docker/

    Architect's Pro Tip

    "For CI/CD pipelines, pin your `docker:latest` base images to a specific SHA digest in your Dockerfile (`FROM image@sha256:...`) to avoid sudden breaks from upstream changes."

    Frequently Asked Questions

    What's the difference between 'failed to solve' and 'failed to export' errors?

    'Failed to solve' happens during the Dockerfile instruction resolution phase (frontend). 'Failed to export' occurs later, when writing the final image layers (backend).

    Does this error always mean my Dockerfile is wrong?

    Not always. It can be caused by external factors like registry downtime, network issues, or a corrupted local cache, even with a perfect Dockerfile.

    How can I prevent this error in production?

    Use a pinned, internal image registry for base images, implement Dockerfile linting in your CI pipeline, and regularly prune builder caches on your build nodes.

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