Fixing 'bad CRC...' error in downloaded zip file

The Zip file format is a data archive format, using this you can compress a set of files and folders in a single file with reduced size. It is a very useful format since you can easily send or receive huge data files over the Internet. At times, you may encounter CRC (Cyclic Redundancy Check) errors while extracting a zip file. The eruption of a CRC error indicates that your zip file has become corrupted and unusable. In such situations, you are not able to retrieve data and have to look up to a backup copy in order to restore the data. However, if no backup is present, you can still recover inaccessible files by using a professional zip repair utility.

As a practical case, you may come across the following error while trying to unzip some important files (from a downloaded zip file) related to your college project:

"Extracting f_0384
bad CRC eb80c9a6 (should be 372500c6)
Warning: the size of the extracted file (1974357) does not match the uncompressed size (1974076) recorded in the zip file "

CRC is a calculation made from all the data in a file to insure accuracy in transmission. When you add a file to a Zip file, WinZip calculates a CRC value for the file and saves the value in the Zip file. When you later extract the file from the Zip file, WinZip calculates the CRC of the extracted file and compares it to the value stored when the file was zipped.

Cause
In the above scenario, the two CRC values do not match, and Win Zip displayed an error. This error indicates that data inside the zip file has got damaged. The possible cause behind data damage is a transfer error while downloading a zip file from the Internet.

Resolution
In order to address the issue, you can try the following steps:

Try and access another copy of the file;ask the source to send another copy
Download the Zip file again, you might recover some files
If nothing works, then you must repair the zip file using zip recovery software

A third-party recovery application is quite easy-to-use and hence, doesn't require any prior technical knowledge. Ensure you download a trusted zip recovery application which doesn't modify the original content.