stride3d/stride · error · InvalidOperationException

Not a valid zip entry.

Error message

Not a valid zip entry.

What it means

ReadFile seeks to the entry's stored header offset and verifies the local file header signature (0x04034b50, 'PK\x03\x04'). A mismatch means the data at that offset is not the expected local entry header, so reading is aborted.

Solutions

1. Re-create the ZipFile and re-query GetAllEntries before reading if the archive may have changed
2. Ensure the ZipFileEntry came from the same ZipFile instance over the same stream
3. Verify the archive's integrity (test extraction or checksum) before reading

Example fix

// before
var entries = oldZip.GetAllEntries(); // stale
using var zip = new ZipFile(newStream);
zip.ReadFile(entries[0]);
// after
using var zip = new ZipFile(newStream);
var entry = zip.GetAllEntries().First(e => e.Filename == name);
zip.ReadFile(entry);

// ensure entries are fresh from the same live ZipFile instance
var freshEntry = liveZip.GetAllEntries().FirstOrDefault(e => e.Filename == entry.Filename);
if (freshEntry is null) throw new InvalidOperationException("Entry no longer exists in archive");

try { zip.ReadFile(entry); }
catch (InvalidOperationException) { throw new InvalidDataException($"Zip entry '{entry.Filename}' has a corrupt header"); }

When it happens

Trigger: Calling ReadFile with a ZipFileEntry whose HeaderOffset points at wrong/garbage data: the archive was modified after entries were listed, offsets came from a different ZipFile instance, or the file was corrupted/truncated.

Common situations: Merging or appending to zip files then reading stale entries, caching entries across stream reopen where the file changed, data-descriptor entries with outdated offsets.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

• Central directory currently does not exist
• Stream cannot seek
• Stream cannot be written
• File doesn't appear to be a valid package
• Package file [ ] was not found

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/55afc04ad9a41520. Report an issue: GitHub.

Appendix: source

Thrown at sources/core/Stride.Core.IO/System.IO.Compression.Zip/ZipFile.cs:456

        /// </summary>
        /// <param name="zfe">
        /// Entry information of file to extract
        /// </param>
        /// <returns>
        /// Stream to store the uncompressed data
        /// </returns>
        /// <remarks>
        /// Unique compression methods are Store and Deflate
        /// </remarks>
        public Stream ReadFile(ZipFileEntry zfe)
        {
            // check signature
            var signature = new byte[4];
            this.zipFileStream.Seek(zfe.HeaderOffset, SeekOrigin.Begin);
            this.zipFileStream.Read(signature, 0, 4);
            if (BitConverter.ToUInt32(signature, 0) != 0x04034b50)
            {
                throw new InvalidOperationException("Not a valid zip entry.");
            }

            // Select input stream for inflating or just reading
            Stream inStream;
            switch (zfe.Method)
            {
                case Compression.Store:
                    inStream = this.zipFileStream;
                    break;
                case Compression.Deflate:
                    inStream = new DeflateStream(this.zipFileStream, CompressionMode.Decompress, true);
                    break;
                default:
                    throw new InvalidOperationException("Not a valid zip entry.");
            }

            this.zipFileStream.Seek(zfe.FileOffset, SeekOrigin.Begin);

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