{"id":"be8bfb4da57ee09c","repo":"gofiber/fiber","slug":"missing-handler-middleware-in-route-s","errorCode":null,"errorMessage":"missing handler/middleware in route: %s\n","messagePattern":"missing handler/middleware in route: (.+?)\n","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"error","filePath":"router.go","lineNumber":981,"sourceCode":"\tnorm := app.normalizePath(path)\n\n\theadStack := app.stack[headIndex]\n\tfor i, headRoute := range slices.Backward(headStack) {\n\t\tif headRoute.path != norm || headRoute.mount || headRoute.use || !headRoute.autoHead {\n\t\t\tcontinue\n\t\t}\n\n\t\tapp.stack[headIndex] = append(headStack[:i], headStack[i+1:]...)\n\t\tapp.hasRoutesRefreshed = true\n\t\tatomic.AddUint32(&app.handlersCount, ^uint32(len(headRoute.Handlers)-1)) //nolint:gosec // G115 - handler count is always small\n\t\treturn\n\t}\n}\n\nfunc (app *App) register(methods []string, pathRaw string, group *Group, handlers ...Handler) {\n\t// A regular route requires at least one ctx handler\n\tif len(handlers) == 0 && group == nil {\n\t\tpanic(fmt.Sprintf(\"missing handler/middleware in route: %s\\n\", pathRaw))\n\t}\n\t// No nil handlers allowed\n\tfor _, h := range handlers {\n\t\tif h == nil {\n\t\t\tpanic(fmt.Sprintf(\"nil handler in route: %s\\n\", pathRaw))\n\t\t}\n\t}\n\n\t// Precompute path normalization ONCE\n\tif pathRaw == \"\" {\n\t\tpathRaw = \"/\"\n\t}\n\tif pathRaw[0] != '/' {\n\t\tpathRaw = \"/\" + pathRaw\n\t}\n\tpathPretty := pathRaw\n\tif !app.config.CaseSensitive {\n\t\tpathPretty = utilsstrings.ToLower(pathPretty)","sourceCodeStart":963,"sourceCodeEnd":999,"githubUrl":"https://github.com/gofiber/fiber/blob/9a4c7e57fe0b080a04235d28a4b0d2b4b353d58c/router.go#L963-L999","documentation":"App.register requires that a regular route (one not created via a Group) has at least one handler or middleware. Calling register with an empty handlers slice and no group panics with \"missing handler/middleware in route\", because there would be nothing to execute for matching requests.","triggerScenarios":"Indirectly via app.Get(\"/path\") with no handler arguments, or any HTTP-method shortcut called with only a path. Internal callers of register that pass no handlers and no group hit this guard too.","commonSituations":"Typing app.Get(\"/health\") and forgetting the handler. Refactoring that removes the handler argument but leaves the route call. Building routes generically and an empty handler slice slips through.","solutions":["Provide at least one handler argument to the route registration method, e.g. app.Get(\"/health\", healthHandler).","When registering programmatically, assert the handlers slice is non-empty before calling register-equivalents.","Use a linter or code review to catch method shortcuts with missing handler args."],"exampleFix":"// before\napp.Get(\"/health\")\n// after\napp.Get(\"/health\", func(c fiber.Ctx) error {\n    return c.SendString(\"ok\")\n})","handlingStrategy":"validation","validationCode":"handlers := []fiber.Handler{ /* built elsewhere */ }\nif len(handlers) == 0 {\n    log.Fatalf(\"route %q has no handler/middleware\", path)\n}\napp.Register(methods, path, handlers...)","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Always pass at least one handler to route-registration methods (Get, Post, etc.).","When building handler slices programmatically, assert non-empty before registering."],"tags":["routing","handler","registration","panic"],"analyzedSha":"9a4c7e57fe0b080a04235d28a4b0d2b4b353d58c","analyzedAt":"2026-08-04T21:44:03.395Z","schemaVersion":2}