Uncompressing a ZIP file despite CRC errors

Question

I have downloaded a multipart ZIP archive. It contains a video file.

Unfortunately, IZarc reports a CRC check fail when extracting the archive. Downloading the archive again is a long task, since I used a freemium digital locker and JDownloader, it will take me several hours to download all files again and I'm even unsure if the result will be better.

So I want to ask: provided that the archive is composed by .zip, .z01 ... .z09 parts, and provided that a few bytes damaged in a video stream don't necessarily make the video unreadable (it's an MP4),

How do I extract a multipart ZIP archive disabling CRC checks or at least preventing the zip utility from deleting a file that fails the check?

Answer 1

Cygwin's zip has the command line switches -F and -FF. They can be used if some portions of the archive are missing.

Use zip -F broken_archive -F --out fixed_archive.zip to create a new ZIP file that contains the same files with hard-fixed CRC, then extract the usual way from the new archive

Answer 2

Landed here due to a Bad CRC error when trying to extract a zip file.

From a terminal, it makes no difference if you are on Linux, *BSD, OSX or Windows (as far as I know).

The correct way to repair a zip with CRC errors is to try the -F method, if it fails try -FF method. That is:

zip -F damaged.zip --out hope.zip
unzip -t hope.zip

If you still see ZIP bad CRC, try:

zip -FF damaged.zip --out morehope.zip
unzip -t morehope.zip

Strong chance you will still see ZIP bad CRC, but always nice to have hope.

At this point there is really only two options.

The first is to remove the damaged file. For example, where fileBadCRC.jpg is the file with the bad CRC:

zip -d damaged.zip fileBadCRC.jpg

Or replace it with another copy (assuming you have a copy to replace the file):

zip damaged.zip fileBadCRC.jpg

Either way, running unzip damaged.zip will now show no errors, but you have lost or replaced the original file that had the error.

Answer 3

How To Bypass CRC Errors And Extract The RAR Archive In WinRAR? You can bypass the CRC error and extract RAR files by using the following steps:

Open WinRAR software and click on the "File" menu and choose the "Open Archive" option Next, browse for the problematic RAR archive and click on the "Open" option Then select the "Extract to" option Extract RAR file with WinRAR

Click the check box next to "Keep Broken Files" in the "Miscellaneous" section Then, provide the path on your PC where you want to uncompress the RAR file on the right side of the window. Click on "OK" to start the extraction Ignore any errors that appear during the RAR file extraction process. When a CRC error window pops up, close it and carry on your extraction process. WinRAR application will permit you to continue and extract the files stored in the RAR archive.