Web3 & Blockchain Errors

Understanding Web3 errors

Web3 errors are unusually terse because the EVM reports failure without explanation by default. execution reverted means a require or revert triggered. The reason string is present in the return data but most libraries discard it. Nonce errors reflect the strict sequential ordering of transactions per account, so a stuck transaction blocks every one behind it.

How to debug Web3 errors

1. Simulate before sending: eth_call against the same block returns the revert reason string that a submitted transaction hides.
2. Use a transaction tracer (Tenderly, Foundry's cast run, or a node's debug_traceTransaction) to see the exact opcode and contract where execution reverted.
3. For nonce errors, query the account's pending nonce (eth_getTransactionCount with the pending tag) rather than tracking it locally.
4. To replace a stuck transaction, resend with the same nonce and a materially higher gas price: most nodes require at least a 10% increase.
5. Check the chain ID matches the network you intend. Signing for the wrong chain produces confusing rejection messages.

Tools worth reaching for

• cast (Foundry)
• eth_call simulation
• Tenderly / block explorer tracer
• debug_traceTransaction

All 7 Web3 errors

• Web3: execution revertedThe smart contract reverted. Solidity custom errors or revert strings often explain the exact requirement that failed.
• Web3: gas required exceeds allowance (0) NewThe node simulated the transaction and found the sender cannot cover it, so the allowance it reports is the gas the…
• Web3: insufficient funds for gas * price + valueThe wallet lacks enough native token to pay transaction value plus gas. This is separate from ERC-20 token balance.
• Web3: intrinsic gas too low NewThe gas limit on the transaction is below the minimum the EVM charges before executing any contract code: 21,000 for a…
• Web3: max fee per gas less than block base fee NewThe node rejected the transaction because its maxFeePerGas is below the base fee of the next block. Base fee moves by…
• Web3: missing revert data in call exception (CALL_EXCEPTION) NewThe call failed without a reason string, which usually means there is no contract at that address on this chain rather…
• Web3: nonce too low / replacement transaction underpricedThe transaction nonce has already been mined, or a replacement transaction did not increase fees enough to replace the…

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.
• 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.
• 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.