Buglyst Blog
Learn to debug under pressure.
Playbooks for fast pattern recognition, guides for the full investigation, and articles for the engineering judgment around the edges.
17 playbooks · 509 guides · 95 articles · 12 linked practice labs ·skip to practice
Fast pattern recognition for the production failures engineers see most often.
3 playbooks in Backend & APIs
Debugging Retry Bugs
Retry issues often hide the first failure and create duplicate work.
Debugging Idempotency Bugs
How to debug duplicate writes when clients, webhooks, or workers retry after ambiguous failures.
Debugging Payment Races
How to reason about duplicate charges, concurrent refunds, and payment workflow compensation.
Structured investigations for the failure modes engineers meet in real systems.
Debugging FastAPI 422 Validation Errors: Pydantic Model Mismatches
A systematic approach to diagnosing and fixing HTTP 422 validation errors in FastAPI, focusing on Pydantic model mismatches and request parsing issues.
FastAPI Background Task Not Running: Debugging Silent Failures
A practical debugging guide for when FastAPI background tasks silently fail to execute, covering lifespan events, async context, and server configuration.
Celery Beat Periodic Task Not Running: A Field Guide
A production-tested guide to diagnosing why your Celery Beat periodic tasks silently fail to execute, covering scheduler locks, timezone mismatches, and worker routing.
gRPC Client-Server Error in Python: Connection Refused and Deadline Exceeded
A practical guide to debugging connection refused, deadline exceeded, and other communication errors in Python gRPC services.
Debugging Go HTTP Client Timeout Errors: Beyond the Obvious
A practical guide to identifying and fixing Go HTTP client timeout errors, covering net/http defaults, context deadlines, DNS issues, and connection pooling gotchas.
gRPC Interceptor Not Executing in Go: Why Your Middleware Is Being Skipped
A debugging guide for when your gRPC interceptor in Go silently fails to execute, covering registration order, interceptor chaining, and server lifecycle quirks.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Debugging Third-Party API Issues: A Systematic Approach
A practical guide to diagnosing and fixing third-party API integration problems, with real-world examples and a step-by-step debugging framework.
Debugging Webhook Delivery Failures: What the Logs Don't Tell You
HTTP 200 doesn't mean your webhook was processed. A practical guide to the network and middleware layers that silently drop webhooks.
Debugging HTTP Headers with curl: From Basic Flags to Packet-Level Inspection
A practical guide to inspecting HTTP request and response headers with curl, covering basic flags, debugging tricky issues, and understanding what your headers are really doing.
Debugging WebSocket Real-Time Features: Packet Loss, Reconnect Storms, and Silent Failures
WebSocket debugging goes beyond console.log. I cover packet capture with tcpdump, reconnect backoff strategies, and a war story about a silent failure that took down a production chat feature.
Rest API Design Mistakes That Inject Bugs Into Your System
Most API bugs aren't in the implementation—they're baked into the contract. Here are the design errors I've seen cause the most production incidents.
Idempotency Keys: The Safety Net Your Payment API Needs
How idempotency keys prevent double charges, lost refunds, and data corruption in payment APIs. With real-world examples and edge cases you haven't considered.