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How to repair zip files?

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WinRAR can create RAR files with an internal recovery record that slightly increases the archive size, but lets you to recover the contents of damaged RAR archives when the corrupted or missing segment is no larger than the size of the recovery record.

However, according to the WinRAR help file, "ZIP archive format does not support the recovery record."
-xtabber (April 25, 2014, 10:13 AM)
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This is why I always use RAR instead of zip when archiving my own stuff. I think the latest zip archive format version has offered some rudimentary recovery data to created archives, but it's nothing nearly as robust as how RAR handles things. Oh, and you can control the size of the recovery record RAR adds as well.

Repairing zip files is always a dicey proposition. It rarely works. I think you'd get better odds in Vegas.

I wonder whether we aren't discussing a non-existent problem.
It might be simply a case where, as @Shades put it:
Always use the latest version of your favorite zip/unzip software. It might be that the person creating the archive has used an option not yet available in the version you have running and you will get this type of error message. ...
-Shades (January 15, 2014, 05:09 AM)
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Has anyone in this discussion thread actually had a repeatable case where their system created a ZIP file that was later found to be invalid and/or corrupted?

If for some reason you would rather not use WinRar for a particular file set you can still build a file set with recovery info using QuickPar and PAR2 files.  For example if you wanted to include par2 files for a data dvd.

Although the most common use in my experience is with file sets posted to usenet.  In most cases the file set is rar files but it doesn't have to be.  :)


Has anyone in this discussion thread actually had a repeatable case where their system created a ZIP file that was later found to be invalid and/or corrupted?
-IainB (April 26, 2014, 11:40 PM)
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Yes, but it was one of two different scenarios, and it was quite some time ago, circa 2001 or so when I was still running Win95 or 98.

1- Zip file that was apparently the victim of a bad sector that hadn't been detected yet.  
    Zipped, tested OK, powered down, next day no zippy pour moi.
2- Accidentally unplugged the computer while creating a zip archive.  
    I thought it had finished before the power went, but apparently not.  

@Edvard: Those were anomalous instances and not repeatable. I could be wrong, of course, but that's what I was trying to point out in my earlier comment - i.e., that this thread is about something (an error or a fix for an error) that doesn't happen under normal circumstances, or isn't actually required, and which couldn't be mitigated or repaired if it occurred anyway.

In other words, there is likely to be no need to repair .ZIP files, as you would probably only get damaged ZIP files from an irreversible anomalous and non-repeatable) event, and due to the simple structure of .ZIP files, you will be unlikely to be able to recover/repair/reconstruct the lost/corrupted data - you couldn't "magic" the data out of nowhere.


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