gofiber/fiber · error

Route '%s' has %d parameters, which exceeds the maximum of %

Error message

Route '%s' has %d parameters, which exceeds the maximum of %d

What it means

parseRoute enforces a hard cap (maxParams = 30) on the number of path parameters in a single route pattern, because the router pre-allocates parameter storage sized to this limit. A pattern with more than 30 parameters panics at registration with the route, the count, and the maximum.

Source

Thrown at path.go:364

	parser.minSlashes = int32(minSlashes)
	if bounded {
		parser.maxSlashes = int32(maxSlashes)
		parser.maxBounded = true
	}
}

// parseRoute analyzes the route and divides it into segments for constant areas and parameters,
// this information is needed later when assigning the requests to the declared routes
func parseRoute(pattern string, regexHandler any, customConstraints ...CustomConstraint) routeParser {
	parser := routeParser{}
	parser.parseRoute(pattern, regexHandler, customConstraints...)
	// The slash bounds only speed up the router's candidate scan; computing them
	// here keeps them off RoutePatternMatch's per-call path, which never reads them.
	parser.computeSlashBounds()

	// Check if the route has too many parameters
	if len(parser.params) > maxParams {
		panic(fmt.Sprintf("Route '%s' has %d parameters, which exceeds the maximum of %d",
			pattern, len(parser.params), maxParams))
	}

	return parser
}

// addParameterMetaInfo add important meta information to the parameter segments
// to simplify the search for the end of the parameter
func addParameterMetaInfo(segs []*routeSegment) []*routeSegment {
	var comparePart string
	segLen := len(segs)
	// loop from end to begin
	for i := segLen - 1; i >= 0; i-- {
		// set the compare part for the parameter
		if segs[i].IsParam {
			// important for finding the end of the parameter
			segs[i].ComparePart = RemoveEscapeChar(comparePart)
		} else {

View on GitHub (pinned to 9a4c7e57fe)

Solutions

1. Reduce the number of path parameters to 30 or fewer by moving extra values into query parameters or the request body.
2. Consolidate related params into a single segment parsed inside the handler.
3. If you genuinely need more, restructure the API into nested sub-routes.

Example fix

// before
app.Get("/:a/:b/:c/:d/.../:ag", handler)
// after
app.Get("/search", handler) // pass filters as query params: /search?a=1&b=2...

// maxParams mirrors the internal router cap (30)
const routeParamCap = 30
func countParams(pattern string) int {
    n := 0
    for i := 0; i < len(pattern); i++ {
        if pattern[i] == ':' || pattern[i] == '*' {
            n++
        }
    }
    return n
}
if countParams(pattern) > routeParamCap {
    log.Fatalf("route %q exceeds the %d parameter cap; move extras to query/body", pattern, routeParamCap)
}

When it happens

Trigger: Registering a route like app.Get("/:a/:b/:c/.../:ae", ...) with more than 30 parameter segments. Also triggered by wildcard/greedy parameters if they each count toward the limit, or by code-generated routes from a schema with many dynamic fields.

Common situations: Auto-generating routes from a database schema or OpenAPI spec with many path params. Building a search/filter URL that encodes each filter as a param. Migration from a router without such a limit.

Related errors

• %s: invalid handler #%d (%T)\n
• route handler 'fn' cannot be nil
• fiber: Config.RegexHandler return type must support MatchStr
• fiber: Config.RegexHandler must not return nil
• fiber: Config.RegexHandler must be a non-nil function

AI-assisted analysis of gofiber/fiber@9a4c7e57fe (2026-08-04). Data as JSON: /data/errors/f2c514efdecb7104.json. Report an issue: GitHub.