{"record":{"id":"f722538c35e2f63e","repo":"gofiber/fiber","slug":"open-file-error-w","errorCode":null,"errorMessage":"open file error: %w","messagePattern":"open file error: %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"client/hooks.go","lineNumber":308,"sourceCode":"\t\tif f.fieldName == \"\" {\n\t\t\tf.fieldName = \"file\" + strconv.Itoa(i+1)\n\t\t}\n\n\t\tif err := addFormFile(mw, f, fileBuf); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\n\treturn nil\n}\n\nfunc addFormFile(mw *multipart.Writer, f *File, fileBuf *[]byte) error {\n\t// If reader is not set, open the file.\n\tif f.reader == nil {\n\t\tvar err error\n\t\tf.reader, err = os.Open(f.path)\n\t\tif err != nil {\n\t\t\treturn fmt.Errorf(\"open file error: %w\", err)\n\t\t}\n\t}\n\n\t// Ensure the file reader is always closed after copying.\n\tdefer f.reader.Close() //nolint:errcheck // not needed\n\n\t// Create form file and copy the content.\n\tw, err := mw.CreateFormFile(f.fieldName, f.name)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"create file error: %w\", err)\n\t}\n\n\tif _, err := io.CopyBuffer(w, f.reader, *fileBuf); err != nil {\n\t\treturn fmt.Errorf(\"failed to copy file data: %w\", err)\n\t}\n\n\treturn nil\n}","sourceCodeStart":290,"sourceCodeEnd":326,"githubUrl":"https://github.com/gofiber/fiber/blob/a105acad6c1e4576a77f01e02973f67e962bb58d/client/hooks.go#L290-L326","documentation":"addFormFile opens the file at f.path with os.Open when no reader was supplied. This wraps the os.Open error: the path does not exist, is not readable, is a directory, or permissions deny access.","triggerScenarios":"Calling File.SetPath with a nonexistent or unreadable path; pointing at a directory; file deleted between scheduling and sending; permission denied under the process's UID.","commonSituations":"Hard-coded paths that don't exist in the deployment; temp files cleaned up before the request fires; container path-permission mismatches; relative paths resolved from an unexpected working directory.","solutions":["Verify the file exists and is readable (os.Stat / os.Open) before queuing the upload.","Use absolute paths, or SetReader with an already-open handle to control lifetime.","Ensure the process has read permission on the file and its parent directory."],"exampleFix":"// before\nf := &client.File{}\nf.SetPath(userPath)\n\n// after\nif _, err := os.Stat(userPath); err != nil {\n    return fmt.Errorf(\"upload file missing: %w\", err)\n}\nf := &client.File{}\nf.SetPath(userPath)","handlingStrategy":"validation","validationCode":"if info, err := os.Stat(path); err != nil {\n    return fmt.Errorf(\"upload file unavailable: %w\", err)\n} else if info.IsDir() {\n    return errors.New(\"upload path is a directory\")\n}","typeGuard":null,"tryCatchPattern":"if _, err := os.Open(path); err != nil {\n    return fmt.Errorf(\"cannot read upload %q: %w\", path, err)\n}","preventionTips":["Use absolute paths for file uploads.","Prefer SetReader with an open handle to control lifetime explicitly.","Stat files before queuing uploads from user-supplied paths."],"tags":["client","multipart","file-upload","filesystem","permissions"],"backgroundTag":null,"analyzedSha":"a105acad6c1e4576a77f01e02973f67e962bb58d","analyzedAt":"2026-08-11T17:33:26.942Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-23T08:17:48.524Z"}