Gin "Response Writer Already Written" Error When Calling Next()
"Superfluous response.WriteHeader call" or similar already-written errors in Gin almost always mean a response was written more than once for the same request...
Category
Go / Gin
Debugging Go services and the Gin web framework.
Gin Route Wildcard Param Collision With Static Subroutes
Gin's router panics at startup (not at request time) when it detects a conflict between a wildcard parameter route and a static route sharing an ambiguous path...
Go "Cannot Use X as Type Y in Assignment" Interface Mismatch
This compile-time error means a value doesn't actually satisfy the interface (or type) you're trying to assign it to — Go's static type checking catches this...
Go "Concurrent Map Read and Map Write" Fatal Error Crash
Go's built-in maps are explicitly not safe for concurrent use — reading and writing the same map from multiple goroutines simultaneously, without...
Go http.Client Timeout Not Working or Leaking Connections
Two distinct but commonly confused issues affect Go's http.Client: a configured timeout that doesn't actually seem to apply, and connections that leak over...
Gin Custom Validation Error Messages Returning Raw Internal Errors
When Gin's binding validation errors are returned to clients as raw, unfriendly text straight from the underlying validator library, it's because the default...
Gin Panic Recovery Middleware Returning Empty 500 Response
Gin's built-in Recovery() middleware correctly prevents a panic from crashing the entire server, but its default behavior returns a 500 status with no response...
Go Channel Deadlock: Fatal Error "All Goroutines Are Asleep"
Unlike a panic, "all goroutines are asleep - deadlock!" is a fatal error the Go runtime itself detects when literally every goroutine in the program is blocked...
Go "Context Deadline Exceeded" Error Handling in HTTP Requests
"Context deadline exceeded" means an operation using a Go context.Context ran longer than its configured deadline allowed — handling it well means both setting...