{"id":"64d24ee555715098","repo":"gofiber/fiber","slug":"file-failed-to-read-file-q-w","errorCode":null,"errorMessage":"file: failed to read file: %q: %w","messagePattern":"file: failed to read file: %q: %w","errorType":"exception","errorClass":"ErrFileRead","httpStatus":null,"severity":"error","filePath":"ctx.go","lineNumber":582,"sourceCode":"// SaveFileToStorage saves any multipart file to an external storage system.\nfunc (c *DefaultCtx) SaveFileToStorage(fileheader *multipart.FileHeader, path string, storage Storage) error {\n\tif fileheader == nil {\n\t\treturn ErrFileHeaderNil\n\t}\n\n\tfile, err := fileheader.Open()\n\tif err != nil {\n\t\treturn fmt.Errorf(\"%w: %q: %w\", ErrFileOpen, fileheader.Filename, err)\n\t}\n\tdefer file.Close() //nolint:errcheck // not needed\n\n\tmaxUploadSize := c.app.config.BodyLimit\n\tif maxUploadSize <= 0 {\n\t\tmaxUploadSize = DefaultBodyLimit\n\t}\n\n\tif fileheader.Size > 0 && fileheader.Size > int64(maxUploadSize) {\n\t\treturn fmt.Errorf(\"%w: %q: %w\", ErrFileRead, fileheader.Filename, fasthttp.ErrBodyTooLarge)\n\t}\n\n\tbuf := bytebufferpool.Get()\n\tdefer bytebufferpool.Put(buf)\n\n\tlimitedReader := io.LimitReader(file, int64(maxUploadSize)+1)\n\tif _, err = buf.ReadFrom(limitedReader); err != nil {\n\t\treturn fmt.Errorf(\"%w: %q: %w\", ErrFileRead, fileheader.Filename, err)\n\t}\n\n\tif buf.Len() > maxUploadSize {\n\t\treturn fmt.Errorf(\"%w: %q: %w\", ErrFileRead, fileheader.Filename, fasthttp.ErrBodyTooLarge)\n\t}\n\n\tdata := append([]byte(nil), buf.Bytes()...)\n\n\tif err := storage.SetWithContext(c.Context(), path, data, 0); err != nil {\n\t\treturn fmt.Errorf(\"%w: %q to %q: %w\", ErrFileStore, fileheader.Filename, path, err)","sourceCodeStart":564,"sourceCodeEnd":600,"githubUrl":"https://github.com/gofiber/fiber/blob/9a4c7e57fe0b080a04235d28a4b0d2b4b353d58c/ctx.go#L564-L600","documentation":"Returned by Ctx.SaveFileToStorage when the uploaded file's declared Size (multipart.FileHeader.Size) already exceeds the configured BodyLimit, before any streaming read begins. It wraps ErrFileRead with the filename and fasthttp.ErrBodyTooLarge. This is the fast pre-check using the size advertised in the multipart header.","triggerScenarios":"A client uploads a file whose Content-Length/declared multipart size is larger than app.config.BodyLimit (or DefaultBodyLimit if unset). SaveFileToStorage compares fileheader.Size against the limit and rejects immediately.","commonSituations":"Forgetting to raise Config.BodyLimit for large uploads, a default 4MB limit catching legitimate media files, or a malicious oversized upload attempt.","solutions":["Raise Config.BodyLimit to accommodate the maximum expected upload size.","Validate file size on the client side before uploading.","Use a reverse proxy (nginx) with client_max_body_size to reject oversized uploads earlier.","Handle the error gracefully and return 413 Payload Too Large to the client."],"exampleFix":"// before\napp := fiber.New() // default body limit catches large uploads\n\n// after\napp := fiber.New(fiber.Config{\n    BodyLimit: 50 * 1024 * 1024, // 50 MB\n})","handlingStrategy":"validation","validationCode":"// Reject oversized uploads before SaveFileToStorage\nlimit := int64(app.Config().BodyLimit)\nif fileHeader.Size > limit {\n    return fiber.ErrFileRead // or a custom 413 response\n}","typeGuard":null,"tryCatchPattern":"if err := c.SaveFileToStorage(fh, path, storage); err != nil {\n    if errors.Is(err, fiber.ErrFileRead) && errors.Is(err, fasthttp.ErrBodyTooLarge) {\n        return c.Status(fiber.StatusRequestEntityTooLarge).\n            SendString(\"file too large\")\n    }\n    return err\n}","preventionTips":["Set Config.BodyLimit to the max upload size you will accept.","Enforce client_max_body_size at the reverse proxy.","Validate file size client-side before uploading."],"tags":["upload","multipart","body-limit","storage","go"],"analyzedSha":"9a4c7e57fe0b080a04235d28a4b0d2b4b353d58c","analyzedAt":"2026-08-04T21:44:03.395Z","schemaVersion":2}