We have a large zip file (25GB) containing mosty pdfs and png files. (about 150000 files)

When we unzip the file using windows explore some of the content is corrupted. Some png files shows content of other png files, some pdf's won't open. Some are ok.

When we unzip the file using 7zip everything is ok. The zip file was packed on a 2008 server sent over ftp and unpacked on a 2008 server.

Have anybody seen anything like this before and can explain why the explore unpack corrupts the files?

It's very concerning that explore doesn't crash or show an error message if it fails.

  • ardamis.com/2011/07/28/… It's probably related to the size (over 4 gb)
    – Martheen
    Feb 7, 2013 at 8:08
  • 1
    Bottom line - don't use Windows' Compressed Folders. You'll be bitten badly on other occasions as well - say if you want to use Unicode filenames (perfectly normal requirement in this day and age on a modern OS, wouldn't you say?)
    – Karan
    Feb 8, 2013 at 5:45

2 Answers 2


ZIP files originaly had a 4,294,967,295 byte size limit, back in 1989 when ZIP was first developed that was more than enough, but now that you can store 10 times that on a micro-SD card the size of a babies nail it is incredibly tiny.

ZIP64 increased this size limit to 18,446,744,073,709,551,615 bytes. However Windows Explorer does not support ZIP64 so the maximum size you can get without problems using only explorer would be approx 4GB.

For more information you can see the Wikipedia page for ZIP file formats

  • 1
    Interesting, however the Wikipedia article you linked to says: "The File Explorer in Windows XP does not support ZIP64, but the Explorer in Windows Vista does." - Since Windows Server 2008 (Which the OP is using) is built on Vista, one would expect it to also have ZIP64 support. So there might be more to the problem than ZIP64 support. Just last week, I couldn't unzip a 49 GB XML file from a 1.8 GB ZIP archive using Windows Explorer in Windows 8.1, which definitely should have ZIP64 support if the Wikipedia article is correct.
    – René
    Sep 14, 2014 at 16:04

I had trouble opening a 5GB zip file copied acrosss the LAN using XCOPY. It would open OK on the source computer that had WinZip installed (Windows XP x86) but wouldn't open on the destination computer (Server 2003 x64) which only had the native zip support.

After I installed WinZip on the destination PC I could open up the file without any corruption warnings

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