#1385 Archives are not created consistently

Frank G

I'm zipping a number of files and other archives (.jar, .war etc. files). The resulting archive is unfortunately not created consistently. I.e. if I create the archive, then rename it and create it again without changing any of the included files, there are some small differences between the created archives.

I detected this because at a later point in time I use Java (6.0_45) to read the contents of the zip archive, and this failed with a CRC error. But only for some of the archives. Typically, there is a difference of 1 or 3 bytes between the archive that can be read by the Java program and the one that can not. 7-Zip does not have any problems opening or testing the archives that fail being read by Java.

I would expect that if I zip a bunch of files twice, I would get the exact same archive each time if the files are untouched.

I use 7-Zip 9.20 on 32 bit Windows 7 Enterprise with 4 GB ram.

The archive is created with
- Archive format: zip
- Compression level: Maximum
- Compression method: Deflate
- Dictionary size: 32 KB
- Word size: 64
- Number of CPU threads: 8 / 8
- Update mode: Add and replace files
- Options unchecked and no Encryption


  • Frank G
    Frank G

    Post awaiting moderation.