QL-Win/QuickLook · error · InvalidDataException

The file is too small to be a minidump.

Error message

The file is too small to be a minidump.

What it means

Thrown by MinidumpReader.ReadHeader when fileLength is less than HeaderSize (32 bytes). A valid Windows minidump must contain at least the 32-byte MINIDUMP_HEADER, so anything smaller cannot be a minidump. This is an InvalidDataException raised before any field is read.

Source

Thrown at QuickLook.Plugin/QuickLook.Plugin.DumpViewer/MinidumpReader.cs:97

            ReadClrVersions(info);
        }
        catch (Exception ex)
        {
            info.ParseError = ex.Message;
        }

        return info;
    }

    private static FileStream OpenRead(string path)
    {
        return new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete);
    }

    private static MinidumpHeader ReadHeader(BinaryReader reader, long fileLength)
    {
        if (fileLength < HeaderSize)
            throw new InvalidDataException("The file is too small to be a minidump.");

        reader.BaseStream.Position = 0;

        var header = new MinidumpHeader
        {
            Signature = reader.ReadUInt32(),
            Version = reader.ReadUInt32(),
            NumberOfStreams = reader.ReadUInt32(),
            StreamDirectoryRva = reader.ReadUInt32(),
            CheckSum = reader.ReadUInt32(),
            TimeDateStamp = reader.ReadUInt32(),
            Flags = reader.ReadUInt64(),
        };

        if (header.Signature != MinidumpSignature)
            throw new InvalidDataException("The file does not have a minidump signature.");

        var directoryBytes = (long)header.NumberOfStreams * DirectoryEntrySize;

View on GitHub (pinned to cb5d9c429c)

Solutions

1. Pre-screen with MinidumpReader.IsMinidump(path) which returns false (never throws) for short files before calling Read.
2. Check File.Exists and new FileInfo(path).Length >= 32 before opening.
3. If the file is expected to be a dump, re-capture it from the crashing process; an undersized dump means the writer was interrupted.
4. Catch InvalidDataException at the plugin boundary and show 'not a minidump' rather than crashing the preview.

Example fix

// before
using var reader = new BinaryReader(OpenRead(path));
var header = ReadHeader(reader, stream.Length);

// after
if (stream.Length < 32) return null; // or IsMinidump(path) guard
var header = ReadHeader(reader, stream.Length);

if (!File.Exists(path) || new FileInfo(path).Length < 32) return; // too small to be a minidump
// or use the built-in safe probe:
if (!MinidumpReader.IsMinidump(path)) return;

static bool CouldBeMinidump(long len) => len >= 32;

try { var info = MinidumpReader.Read(path); }
catch (InvalidDataException ex) when (ex.Message.Contains("too small")) { /* show 'not a minidump' */ }

When it happens

Trigger: Calling MinidumpReader.Read (or ReadHeader) on a file whose Length < 32. Common with empty placeholder files, a 0-byte download, or a file of a different type whose path/extension was assumed to be a .dmp.

Common situations: Previewing a path that QuickLook routed to DumpViewer but the file is empty or only a few bytes; an aborted crash-dump write; a symlink/placeholder; a non-dump file passed because only extension matching was done.

Related errors

• The file does not have a minidump signature.
• The minidump stream directory is outside the file.
• DOS signature not found.
• Thumbs.db not found.
• DS_Store: unknown record type '{stype}'

AI-assisted analysis of QL-Win/QuickLook@cb5d9c429c (2026-08-13). Data as JSON: /api/errors/a892cd3a1c72c3e1. Report an issue: GitHub.