gofiber/fiber · error

failed to bind to response headers: %w

Error message

failed to bind to response headers: %w

What it means

Returned by the middleware (idempotency.go:154-156) when c.Bind().RespHeader(headers) fails while building the cached response. Binding response headers into a map[string][]string rarely fails — it would require an internal fiber/v3 binding error.

Source

Thrown at middleware/idempotency/idempotency.go:155

		} else if ok {
			return nil
		}

		// Execute the request handler
		if err := c.Next(); err != nil {
			// If the request handler returned an error, return it and skip idempotency
			return err
		}

		// Construct response
		res := &response{
			StatusCode: c.Response().StatusCode(),
			Body:       c.Response().Body(),
		}
		{
			headers := make(map[string][]string)
			if err := c.Bind().RespHeader(headers); err != nil {
				return fmt.Errorf("failed to bind to response headers: %w", err)
			}

			if keepResponseHeaders == nil {
				// Keep all
				res.Headers = headers
			} else {
				// Filter
				res.Headers = make(map[string][]string)
				for h, vals := range headers {
					if shouldKeepHeader(h) {
						res.Headers[h] = vals
					}
				}
			}
		}

		// Marshal response
		bs, err := res.MarshalMsg(nil)

View on GitHub (pinned to 9a4c7e57fe)

Solutions

1. Confirm you are on a compatible fiber/v3 release.
2. If you overrode the binder via app.NewCtx or custom Bind, validate its RespHeader path.
3. File an upstream issue — this path should be infallible.

// at startup, exercise the binder path
h := make(map[string][]string)
// simulate via a test ctx if available; otherwise pin fiber version

When it happens

Trigger: Effectively unreachable in normal fiber operation; would require a fiber/v3 regression in the RespHeader binder, or a custom binder override that returns an error.

Common situations: Not seen in production. If hit, suspect an incompatible fiber/v3 patch version or a custom Bind implementation.

Related errors

• binder: custom binder not found, please be sure to enter the
• failed to marshal response: %w
• min constraint requires an argument
• max constraint requires an argument
• range constraint requires two arguments

AI-assisted analysis of gofiber/fiber@9a4c7e57fe (2026-08-04). Data as JSON: /data/errors/b9778f4e6389ed8c.json. Report an issue: GitHub.