Docker Core
BuildKit aborted the build because a step exited with a failing code.
failed-to-solveReviewed for reference consistency: August 11, 2026
BuildKit aborted the build because a step exited with a failing code.
What failed-to-solve Means
The failed-to-solve error on the Docker Core indicates buildkit aborted the build because a step exited with a failing code.. This typically occurs due to the step's command returned a non-zero exit code.
BuildKit reports build failures in a solve envelope: the failed-to-solve headline carries the step identifier, the executed command, and the exit code. The envelope is diagnostic structure around an ordinary build-step failure rather than a builder malfunction.
How to fix failed-to-solve
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List the builder instances available
The buildx listing shows which builders exist and which is default, framing where the solve ran.
docker buildx lsRe-run with full progress output
The plain progress mode prints each step's complete output, exposing the failing command's own messages above the envelope.
docker buildx build --progress plain -f Dockerfile .
Technical Background
BuildKit separates orchestration from execution: the solve envelope is the orchestration view, and the exit code inside it is the executor's verdict on the step's own command.
The headline bundles what older builder output spread across screens: which frontend ran, which process failed, and with what status, so the tail of the line usually carries everything needed to locate the failing instruction in the Dockerfile.
Common Causes
- The step's command returned a non-zero exit code
- A referenced file is missing from the build context
- A base image or dependency became unavailable mid-build
Typical Scenarios
- A RUN step whose package install failed against a stale package index
- A compile error inside a source file newly added to the build context
- A COPY referencing a file excluded by the ignore rules
What to Know
Reading bottom-up helps: the exit code identifies the step type, the quoted command identifies the Dockerfile line, and the log above the envelope holds the failing step's own output.
Frequently Asked Questions
Common questions about Docker failed-to-solve error
No, the builder worked. The envelope reports a completed evaluation where a build step returned failure; the build did not, BuildKit did its job.
BuildKit streams only the failing step's output by default, hiding successful steps, which concentrates the relevant log but can feel abrupt.
Related Error Codes
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