{"record":{"id":"d3efbe53b172f832","repo":"AlistGo/alist","slug":"failed-to-open-image-w","errorCode":null,"errorMessage":"failed to open image: %w","messagePattern":"failed to open image: %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"warning","filePath":"drivers/local/util.go","lineNumber":121,"sourceCode":"\t\tWithOutput(outBuffer, os.Stderr). // Capture stdout to outBuffer, stderr to os.Stderr\n\t\t// ErrorToStdOut(). // Alternative: send ffmpeg's stderr to Go's stdout\n\t\tRun()\n\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"ffmpeg-go failed to resize image %s to buffer: %w\", inputFile, err)\n\t}\n\tif outBuffer == nil || outBuffer.Len() == 0 {\n\t\treturn nil, fmt.Errorf(\"ffmpeg-go produced empty buffer for %s\", inputFile)\n\t}\n\n\treturn outBuffer, nil\n}\n\nfunc generateThumbnailWithImagingOptimized(imagePath string, targetWidth int, quality int) (*bytes.Buffer, error) {\n\n\tfile, err := os.Open(imagePath)\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"failed to open image: %w\", err)\n\t}\n\tdefer file.Close()\n\n\timg, err := imaging.Decode(file, imaging.AutoOrientation(true))\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"failed to decode image: %w\", err)\n\t}\n\n\tthumbImg := imaging.Resize(img, targetWidth, 0, imaging.Lanczos)\n\timg = nil\n\n\tvar buf bytes.Buffer\n\t// imaging.Encode\n\t// imaging.PNG, imaging.JPEG, imaging.GIF, imaging.BMP, imaging.TIFF\n\toutputFormat := imaging.JPEG\n\tencodeOptions := []imaging.EncodeOption{imaging.JPEGQuality(quality)}\n\n\t// outputFormat := imaging.PNG","sourceCodeStart":103,"sourceCodeEnd":139,"githubUrl":"https://github.com/AlistGo/alist/blob/843d9dc8149126976b2625911e45a4d3ffd6f2f5/drivers/local/util.go#L103-L139","documentation":"generateThumbnailWithImagingOptimized calls os.Open on the image path and Go's standard library failed. The wrapped *PathError explains the cause: ENOENT (file removed since listing), EACCES (permission denied for the process user), or EMFILE (too many open file descriptors under heavy thumbnail traffic).","triggerScenarios":"Thumbnail request racing with file deletion, read permissions not granted to the alist/OpenList process user, NFS/SMB mount not yet mounted or stale, or fd exhaustion when many thumbnails are generated concurrently.","commonSituations":"Media directory on a network mount that dropped; files renamed/deleted by another process between list and thumb requests; systemd/docker service user lacking read access to the media folder.","solutions":["Check the wrapped PathError for the syscall reason (no such file / permission denied / too many open files)","Confirm the process user can read the file: sudo -u <alistuser> head -c1 <path>","If EMFILE, raise the file descriptor limit (ulimit -n / LimitNOFILE) or reduce concurrent thumbnail workers","If files are transiently missing, treat the error as non-fatal and skip caching the thumbnail"],"exampleFix":null,"handlingStrategy":"validation","validationCode":"func canRead(path string) bool {\n    f, err := os.Open(path)\n    if err != nil {\n        return false\n    }\n    f.Close()\n    return true\n}","typeGuard":null,"tryCatchPattern":"Check errors.Is(err, fs.ErrNotExist) || errors.Is(err, fs.ErrPermission): for ErrNotExist skip silently (file raced away); for ErrPermission log once per directory; for EMFILE throttle concurrency.","preventionTips":["Run the process with read access to all media roots","Raise LimitNOFILE / ulimit -n when serving large libraries","Handle deletion races by treating ENOENT as 'no thumbnail', not an error"],"tags":["filesystem","permissions","thumbnail","local-driver"],"backgroundTag":null,"analyzedSha":"843d9dc8149126976b2625911e45a4d3ffd6f2f5","analyzedAt":"2026-08-15T12:14:11.722Z","schemaVersion":2},"datasetVersion":"2026-08-15T17:31:12.345Z"}