{"record":{"id":"cc93313bf56ebf96","repo":"valyala/fasthttp","slug":"fasthttp-there-is-no-uploaded-file-associated-wit","errorCode":null,"errorMessage":"fasthttp: there is no uploaded file associated with the given key","messagePattern":"fasthttp: there is no uploaded file associated with the given key","errorType":"error_code","errorClass":null,"httpStatus":null,"severity":"error","filePath":"server.go","lineNumber":1169,"sourceCode":"// before FormFile.\nfunc (ctx *RequestCtx) FormFile(key string) (*multipart.FileHeader, error) {\n\tmf, err := ctx.MultipartForm()\n\tif err != nil {\n\t\treturn nil, err\n\t}\n\tif mf.File == nil {\n\t\treturn nil, ErrMissingFile\n\t}\n\tfhh := mf.File[key]\n\tif fhh == nil {\n\t\treturn nil, ErrMissingFile\n\t}\n\treturn fhh[0], nil\n}\n\n// ErrMissingFile may be returned from FormFile when the is no uploaded file\n// associated with the given multipart form key.\nvar ErrMissingFile = errors.New(\"fasthttp: there is no uploaded file associated with the given key\")\n\n// SaveMultipartFile saves multipart file fh under the given filename path.\n//\n// The path is used as-is and must be a server-trusted destination filename.\n// Do not pass the attacker-controlled fh.Filename directly without validating\n// it and constraining it to the intended destination directory.\nfunc SaveMultipartFile(fh *multipart.FileHeader, path string) (err error) {\n\tvar (\n\t\tf  multipart.File\n\t\tff *os.File\n\t)\n\tf, err = fh.Open()\n\tif err != nil {\n\t\treturn err\n\t}\n\n\tvar ok bool\n\tif ff, ok = f.(*os.File); ok {","sourceCodeStart":1151,"sourceCodeEnd":1187,"githubUrl":"https://github.com/valyala/fasthttp/blob/c96f600972c6f4a7a30d664257b340ebe9d60124/server.go#L1151-L1187","documentation":"ErrMissingFile is exported by fasthttp and returned from RequestCtx.FormFile when the multipart form contains no uploaded file under the requested key. It signals a lookup miss on the multipart file map, not a parse failure.","triggerScenarios":"Calling ctx.FormFile(\"upload\") when the client posted no file field named \"upload\", or posted it under a different name, or the request was not multipart/form-data.","commonSituations":"Frontend form field renamed without updating the backend key; users submitting the form without attaching a file; sending JSON body instead of multipart when the handler expects a file upload.","solutions":["Check the request is multipart and the field name matches exactly what the client sends.","Handle the error explicitly: respond 400 if the file is optional-absent, or use ctx.FormValue defaults.","Inspect ctx.Request.MultipartForm to enumerate available keys for debugging."],"exampleFix":"// before\nfile, err := ctx.FormFile(\"upload\")\n// after\nfile, err := ctx.FormFile(\"upload\")\nif err == fasthttp.ErrMissingFile {\n    ctx.SetStatusCode(400)\n    ctx.SetBodyString(\"no file uploaded under key 'upload'\")\n    return\n}","handlingStrategy":"try-catch","validationCode":"if ctx.Request.Header.MultipartForm() == nil {\n    // request is not multipart; no file can be retrieved\n}","typeGuard":null,"tryCatchPattern":"file, err := ctx.FormFile(\"upload\")\nif errors.Is(err, fasthttp.ErrMissingFile) {\n    ctx.SetStatusCode(400)\n    return\n}\nif err != nil {\n    ctx.SetStatusCode(500)\n    return\n}","preventionTips":["Keep client form field names and server FormFile keys in sync (shared constant/docs).","Decide whether the file is required; 400 on ErrMissingFile, 500 on other errors.","Log available multipart keys when the expected key is missing to aid debugging."],"tags":["multipart","file-upload","http"],"backgroundTag":"missing-multipart-file","analyzedSha":"c96f600972c6f4a7a30d664257b340ebe9d60124","analyzedAt":"2026-08-31T22:48:28.265Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-08T05:18:18.240Z"}