Docker & Container Errors
Daemon connectivity, disk space, image pulls, ports and architecture mismatches.
Understanding Docker errors
Docker errors are usually about the daemon (not running, or not reachable by your user), the host (disk full, port already bound), or the image (wrong architecture, rate-limited pull, missing credentials). Apple Silicon and ARM cloud instances made architecture mismatches far more common. exec format error is the signature, and it means an amd64 binary is being run on arm64 or vice versa.
How to debug Docker errors
- Check the daemon before anything else:
docker info. A "cannot connect to the Docker daemon" error is a socket permission or service problem, never an image problem. - Reclaim space deliberately with
docker system dfto see where it went, thendocker system prune. Build cache and dangling volumes are usually the bulk of it. - For
exec format error, rundocker image inspect --format '{{.Architecture}}' image:tagand compare withuname -m. Build multi-arch images withdocker buildx build --platform linux/amd64,linux/arm64. - Find what is holding a port with
ss -tulpn | grep :PORT(orlsof -i :PORT) rather than restarting Docker and hoping. - Read build failures from the first error, not the last. BuildKit prints failing steps out of order, and the final line is often a downstream consequence.
Tools worth reaching for
docker infodocker system dfdocker buildxss -tulpndocker logs --tail 100
All 27 Docker errors
- Docker build: failed to compute cache key, not found NewA COPY or ADD source does not exist in the build context. The context is the directory sent to the daemon, not your…
- Docker build: layer caching issuesDocker build failing or not using cache properly, resulting in slow builds or unexpected behaviour.
- docker buildx: no builder instance found Newbuildx needs a builder backed by BuildKit. On a fresh install, in CI, or after docker context switching there may be…
- Docker Compose: dependency failed to start: container is unhealthy NewA service waited on another with condition service_healthy and that container's healthcheck never passed. The…
- Docker Compose: network configuration errorDocker Compose cannot create or connect to network. Name conflict, subnet overlap, or network driver issues.
- docker push: unauthorized: authentication required NewThe registry refused the push. Either you are not logged in to that registry host, the token has expired, or the image…
- Docker registry: 429 too many requestsRegistry (e.g., Docker Hub) rate limits unauthenticated or high-volume pulls.
- docker-compose: command not found NewCompose V1, the standalone Python binary invoked as docker-compose, reached end of life and is no longer installed…
- Docker: Cannot connect to the Docker daemonDocker client cannot communicate with Docker daemon. Daemon not running, socket permissions issue, or wrong socket path.
- Docker: container name already in useAttempting to create container with name that's already taken by existing container (running or stopped).
- Docker: could not find an available, non-overlapping IPv4 address pool NewDocker ran out of private subnets to hand to a new bridge network. Either dozens of stale Compose networks are still…
- docker: could not select device driver with capabilities: [[gpu]] New--gpus needs the NVIDIA container toolkit registered as a runtime with the daemon; having the driver installed on the…
- Docker: error getting credentials - credential helper not installedDocker is configured to use a credential helper such as docker-credential-desktop, but that helper is not installed or…
- Docker: exec /app/entrypoint.sh: permission denied NewThe entrypoint script is not executable inside the image. Git records only one permission bit, so a script committed…
- Docker: exec format error (multi-arch)Container binary architecture doesn't match the host (e.g., trying to run amd64 container on Apple Silicon M1/M2/M3…
- Docker: exec user process caused "exec format error"Container binary architecture doesn't match host (e.g., trying to run ARM binary on x86). Or missing shebang in script.
- Docker: failed to solve (process did not complete successfully) NewA RUN instruction exited non-zero during a BuildKit build. The wrapper message is generic; the real error is in the…
- Docker: image not foundSpecified Docker image does not exist in the registry, wrong image name, or missing tag specification.
- Docker: image's platform (linux/amd64) does not match the detected host NewThe image has no build for the host architecture, so Docker Desktop runs it under emulation on Apple Silicon. It is a…
- docker: invalid reference format NewDocker could not parse the image name. The usual causes are an uppercase letter in the repository part, a shell…
- docker: manifest unknown NewThe registry has the repository but not the tag or digest you asked for. Common causes are a typo, a tag that was…
- Docker: no matching manifest for linux/arm64 NewThe image exists but was never published for your CPU architecture. This is routine on Apple Silicon and on ARM cloud…
- Docker: no space left on deviceDocker has run out of disk space for images, containers, or volumes. /var/lib/docker partition is full or Docker…
- Docker: OCI runtime create failed (executable file not found) NewThe container was created but runc could not start the entrypoint. The binary named in CMD or ENTRYPOINT does not…
- Docker: port is already allocatedCannot bind container port because host port is already in use by another container or process.
- Docker: pull rate limit exceededDocker Hub anonymous pull rate limit exceeded (100 pulls per 6 hours). Need authentication or use alternative registry.
- Podman: short-name did not resolve to an alias NewUnlike Docker, Podman does not assume Docker Hub for an unqualified image name. In non-interactive mode it refuses to…
Other categories
- AI 35Rate limits, context windows, GPU memory and model-serving failures.
- Ansible 10Unreachable hosts, become passwords, undefined variables and Jinja2 failures.
- API 14Auth headers, payload limits, versioning, idempotency and webhook signatures.
- Apple 10Command line tools, dyld, Homebrew permissions, notarisation and Keychain.
- Auth 11OIDC, SAML, Auth0, Okta, Keycloak, passkeys and MFA failures.
- BigData 11Spark, Kafka, Airflow, Snowflake, Flink and Databricks failures.
- C# 12NuGet restore, null references, EF Core migrations, async deadlocks and Blazor…
- C++ 11Segfaults, linker errors, memory corruption and template deduction failures.
- Caching 10Cache stampedes, stale content, Varnish and CloudFront failures.
- CI/CD 18GitHub Actions, GitLab CI, Jenkins, CircleCI: permissions, runners and…
- Client 21CORS, mixed content, module resolution, memory limits and framework runtime…
- Cloud 25IAM permissions, quotas, service limits and credential failures.
- Dart 10Null safety, pub version solving and build toolchain problems.
- Database 41Connections, deadlocks, constraints, replication and memory limits.
- DNS 10NXDOMAIN, SERVFAIL, timeouts, propagation and delegation problems.
- Elixir 9GenServer timeouts, supervision failures and Mix compilation problems.
- Email 8Delivery failures, relay denial, authentication, SPF, DKIM and DMARC.
- Frontend 23Hydration mismatches, bundler resolution, layout shift and font loading.
- Git 20Merge conflicts, rejected pushes, detached HEAD, LFS and repository corruption.
- Go 19Nil map assignment, concurrent map access, context cancellation and deadlocks.
- GraphQL 13Validation, depth limits, N+1 queries and fragment problems.
- gRPC 10Status codes, deadlines, message limits, TLS and HTTP/2 transport failures.
- HTTP 494xx client errors, 5xx server errors, redirects, headers and protocol problems.
- ICMP 23Destination unreachable, time exceeded, fragmentation needed and redirects.
- Ingress 8404 default backend, missing TLS secrets, IngressClass and path matching.
- Java 19Class loading, dependency resolution, connection pools and JVM version…
- JavaScript 42npm resolution, async pitfalls, hydration, memory limits and runtime type…
- Kubernetes 34CrashLoopBackOff, ImagePullBackOff, OOMKilled, RBAC, scheduling and storage.
- Logging 9Log4j, Logback, Fluentd, Logstash and CloudWatch ingestion problems.
- MessageQueue 14Kafka, RabbitMQ, SQS, NATS and Celery: lag, rebalancing and poison messages.
- Mobile 17Gradle, CocoaPods, Xcode signing, Metro bundler and toolchain mismatches.
- Monitoring 12Prometheus scrapes, Grafana data sources, OpenTelemetry exporters and agent…
- Network 35Refused connections, timeouts, resets, MTU problems and port exhaustion.
- Performance 6GC pauses, thread pool starvation and event loop blocking.
- PHP 11Memory limits, execution timeouts, autoloading, Composer and PDO connections.
- Proxy 17nginx, Envoy, HAProxy, Traefik, Caddy and Cloudflare upstream failures.
- Python 35Imports, virtual environments, encoding, concurrency and dependency conflicts.
- Regex 8Catastrophic backtracking, back references, escaping and engine differences.
- Ruby 11Bundler, migrations, native extensions, encoding and asset compilation.
- Rust 19Borrow checker, ownership moves, trait bounds and lifetime mismatches.
- Scala 6Dependency resolution, binary compatibility and type inference failures.
- Security 25JWT validation, CSRF, OAuth grants, SELinux, SSH host keys and CSP.
- Serverless 11Lambda timeouts, package size limits, VPC networking and cold starts.
- Shell 13Command not found, permissions, quoting, expansion and Makefile syntax.
- Storage 13S3 permissions, NFS mounts, quotas, signed URLs and volume attachment.
- Svelte 10Store subscriptions, load functions and server/client boundaries.
- System 26Disk space, systemd units, file descriptors, OOM killer and scheduled jobs.
- Terraform 18State locks, provider auth, drift, dependency cycles and plan-time unknowns.
- Testing 18Jest, pytest, JUnit, Cypress and Playwright: fixtures, snapshots and timeouts.
- TLS 24Untrusted authorities, expiry, hostname mismatch, chains and cipher negotiation.
- TypeScript 19Assignability, missing declarations, strict null checks and generic constraints.
- Virtualization 8VirtualBox, VMware, Hyper-V, WSL, KVM and hypervisor conflicts.
- Web3 7Gas estimation, nonce management and reverted transactions.
- WebAssembly 7Compile errors, memory bounds and host binding mismatches.
- WebServer 10nginx, Apache, IIS and Caddy: binding, permissions, rewrites and TLS.
- Windows 10Installer failures, missing runtimes, update errors and permission problems.