Message Queue & Streaming Errors
Kafka, RabbitMQ, SQS, NATS and Celery: lag, rebalancing and poison messages.
Understanding MessageQueue errors
Queue errors are usually about the balance between producers and consumers. Growing lag means consumers cannot keep up. Endless rebalancing usually means consumers are being evicted for exceeding a poll or heartbeat interval, not that the cluster is unhealthy. A poison message, one that always fails processing, will block an ordered partition forever unless there is a dead-letter path, which is why a DLQ is not optional in production.
How to debug MessageQueue errors
- Measure lag over time, not once:
kafka-consumer-groups --describe --group <g>. The trend distinguishes a throughput problem from a stuck consumer. - For repeated rebalancing, compare processing time per batch against
max.poll.interval.ms. Slow processing looks exactly like a dead consumer to the coordinator. - Always configure a dead-letter queue with a bounded retry count. Without one, a single malformed message stops the partition indefinitely.
- Check message size against the broker limit before assuming a network failure: SQS caps at 256 KB, Kafka at
message.max.bytes. - Verify consumer ACLs and topic authorisation separately from connectivity; an authorisation failure often surfaces as a metadata error.
Tools worth reaching for
kafka-consumer-groupsrabbitmqctl list_queuesaws sqs get-queue-attributeskafkacat / kcatflower (Celery)
All 14 MessageQueue errors
- AWS SQS: Message too large (256KB limit)The SQS message body exceeds the 256KB maximum size limit.
- Celery: WorkerLostErrorA Celery worker process died unexpectedly during task execution, often due to OOM kill, segfault, or os._exit() in the…
- Kafka: LEADER_NOT_AVAILABLEPartition has no elected leader. Broker down, ISR empty, or topic just created and metadata not propagated.
- Kafka: Offset out of rangeConsumer trying to read from offset that doesn't exist. Data retention deleted old messages.
- Kafka: RecordTooLargeException NewA message exceeded a size limit. Three separate limits must agree: the producer's max.request.size, the broker or…
- Kafka: Topic authorization failedThe Kafka client does not have the required ACL permissions to produce to or consume from the topic.
- Kafka: UNKNOWN_TOPIC_OR_PARTITION NewThe client asked for a topic the broker does not know about. Either the topic genuinely does not exist, auto-creation…
- Message Queue: Consumer lag too highMessages accumulating faster than consumers can process. Queue backlog growing.
- Message Queue: Poison message blocking queueMessage causing consumer to crash repeatedly. Message stuck in queue blocking other messages.
- NATS: Slow consumer detectedA NATS subscriber cannot process messages fast enough and its pending message buffer is full. The server may…
- RabbitMQ: connection blocked by a resource alarm NewThe broker raised a memory or disk alarm and stopped reading from publishing connections. Consumers keep working…
- RabbitMQ: Connection refusedCannot connect to RabbitMQ server. Service not running, wrong port, or firewall blocking.
- RabbitMQ: PRECONDITION_FAILED - inequivalent arg for queue NewThe queue already exists with different properties than the ones being declared: durability, TTL, dead-letter routing…
- RabbitMQ: Queue length limit exceededA queue has reached its maximum length policy. New messages are being dropped or dead-lettered.
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.
- Docker 27Daemon connectivity, disk space, image pulls, ports and architecture mismatches.
- 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.
- 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.