nilaoda/N_m3u8DL-RE · error · FileNotFoundException

{DecryptionBinaryPath}

Error message

{DecryptionBinaryPath}

What it means

DoWorkAsync validates that a user-supplied decryption binary (--decryption-binary-path) actually exists on disk when keys are provided. The thrown FileNotFoundException's message is the path itself, so the error text is the missing file path.

Solutions

1. Correct --decryption-binary-path to the full absolute path of the binary
2. Verify the file exists: ls <path> / dir <path>
3. Reinstall mp4decrypt (from Bento4) or shaka-packager and use the new path
4. Run from a working directory where the relative path resolves, or switch to an absolute path

Example fix

// before
--decryption-binary-path mp4decrypt
// after
--decryption-binary-path /usr/local/bin/mp4decrypt

if (!string.IsNullOrEmpty(decryptionBinaryPath) && !File.Exists(decryptionBinaryPath))
    throw new FileNotFoundException($"decryption binary missing: {decryptionBinaryPath}");

static bool DecryptionBinaryValid(CLIOptions o) => string.IsNullOrEmpty(o.DecryptionBinaryPath) || File.Exists(o.DecryptionBinaryPath);

try { await DoWorkAsync(option); }
catch (FileNotFoundException ex) when (ex.FileName == null && ex.Message.Contains("decrypt") || ex.Message.EndsWith(".exe"))
{
    Console.Error.WriteLine($"decryption binary not found: {ex.Message}");
}

When it happens

Trigger: option.DecryptionBinaryPath is set (e.g. via --decryption-binary-path) and non-empty, but File.Exists returns false, while option.Keys or --key-text-file indicates decryption will be needed.

Common situations: Typo in the path to mp4decrypt/shaka-packager; binary moved after an upgrade; relative path resolved from a different working directory; Windows users quoting the path incorrectly.

Understand the failure class

Background: "File not found" and ENOENT errors: why libraries can't find a file that should exist — this error's family across 50 libraries.

Related errors

• must be valid 16-byte HEX or Base64. Input string
• Input must be KEY or KID:KEY format.
• MuxAfterDone disabled, MuxImports not allowed!
• ResString.shakaPackagerNotFound
• Invalid Speed Limit

AI-assisted analysis of nilaoda/N_m3u8DL-RE@e113dee70c (2026-09-13). Data as JSON: /api/errors/f336442aa0b6ba6e. Report an issue: GitHub.

Appendix: source

Thrown at src/N_m3u8DL-RE/Program.cs:156

        Logger.Extra($"ffmpeg => {option.FFmpegBinaryPath}");

        // 预先检查mkvmerge
        if (option is { MuxOptions.UseMkvmerge: true, MuxAfterDone: true })
        {
            option.MkvmergeBinaryPath ??= GlobalUtil.FindExecutable("mkvmerge");
            if (string.IsNullOrEmpty(option.MkvmergeBinaryPath) || !File.Exists(option.MkvmergeBinaryPath))
            {
                throw new FileNotFoundException(ResString.mkvmergeNotFound);
            }
            Logger.Extra($"mkvmerge => {option.MkvmergeBinaryPath}");
        }

        // 预先检查
        if (option.Keys is { Length: > 0 } || option.KeyTextFile != null)
        {
            if (!string.IsNullOrEmpty(option.DecryptionBinaryPath) && !File.Exists(option.DecryptionBinaryPath))
            {
                throw new FileNotFoundException(option.DecryptionBinaryPath);
            }
            switch (option.DecryptionEngine)
            {
                case DecryptEngine.SHAKA_PACKAGER:
                {
                    var file = FindShakaPackager();
                    if (file == null) throw new FileNotFoundException(ResString.shakaPackagerNotFound);
                    option.DecryptionBinaryPath = file;
                    Logger.Extra($"shaka-packager => {option.DecryptionBinaryPath}");
                    break;
                }
                case DecryptEngine.MP4DECRYPT:
                {
                    var file = GlobalUtil.FindExecutable("mp4decrypt");
                    if (file == null) throw new FileNotFoundException(ResString.mp4decryptNotFound);
                    option.DecryptionBinaryPath = file;
                    Logger.Extra($"mp4decrypt => {option.DecryptionBinaryPath}");
                    break;

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