pxb1988/dex2jar · error · ZipException

signature not found; was

Error message

 signature not found; was 

What it means

throwZipException builds the standard 'X signature not found; was 0x????????' message: an expected 4-byte record magic was absent at the position where a zip structure (local file header, central directory entry, EOCD) was being read, and the bytes actually found are reported in hex.

Solutions

1. Re-obtain or repair the archive (zip -FF)
2. Check for prepended bytes and recompute the real central directory offset
3. Validate the file is a zip before parsing (check EOCD and signatures)

Example fix

null

// verify central directory offset region begins with CENSIG before deep parsing
raf.position(centralDirOffset);
if (raf.getInt() != 0x02014b50) throw new IOException("central dir signature missing");

null

try { ZipFile z = new ZipFile(f); } catch (ZipException e) { log.error(e.getMessage()); /* message already contains found magic in hex */ }

When it happens

Trigger: Reading a central directory entry or local file header whose magic does not match (CENSIG/LOCSIG), usually because offsets are wrong or the file is corrupted/not a zip.

Common situations: Corrupted or hand-modified zips/APKs, wrong central directory offset after prepended data, parsing non-zip files as zips.

Understand the failure class

Background: Checksum mismatch errors: "checksum verification failed", "digest mismatch", "expected vs actual checksum" — what they mean and how to fix them — this error's family across 41 libraries.

Related errors

• File too short to be a zip file:
• End Of Central Directory signature not found
• File too small to be a dex/zip
• Can not find classes.dex in zip file
• File too small to be a dex/zip

AI-assisted analysis of pxb1988/dex2jar@b5bda4fb49 (2026-09-08). Data as JSON: /api/errors/3e02b4c7df2136ba. Report an issue: GitHub.

Appendix: source

Thrown at dex-reader/src/main/java/com/googlecode/d2j/util/zip/ZipFile.java:270

        // We have to do this now (from the constructor) rather than lazily because the
        // public API doesn't allow us to throw IOException except from the constructor
        // or from getInputStream.
        ByteBuffer buf = (ByteBuffer) raf.duplicate().order(ByteOrder.LITTLE_ENDIAN).position((int) centralDirOffset);
        entries = new ArrayList<>(numEntries);
        for (int i = 0; i < numEntries; ++i) {
            ZipEntry newEntry = new ZipEntry(buf, skipCommentsAndExtra);
            if (newEntry.localHeaderRelOffset >= centralDirOffset) {
                // Ignore the entry
                // throw new ZipException("Local file header offset is after central directory");
            } else {
                entries.add(newEntry);
            }
        }
    }

    static void throwZipException(String msg, int magic) throws ZipException {
        final String hexString = String.format("0x%08x", magic);
        throw new ZipException(msg + " signature not found; was " + hexString);
    }

    @Override
    public void close() throws IOException {
        if(file!=null){
            file.close();
        }
    }

    static class ZipInflaterInputStream extends InflaterInputStream {
        private final ZipEntry entry;
        private long bytesRead = 0;

        public ZipInflaterInputStream(InputStream is, Inflater inf, int bsize, ZipEntry entry) {
            super(is, inf, bsize);
            this.entry = entry;
        }

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