Tuesday, July 20, 2010

Performing ZIP repair after improper download from the Internet

Most of you would have used the file compression feature sometime or the other. It is a very useful feature that is used to squeeze your bulky files into a much smaller data packet. Usually, such data packet is saved in the ZIP extension. These files are extremely useful when you have to send these over the Internet. These ZIP files can be extracted using various file extracting applications. However, sometimes these ZIP files do get corrupt thereby disabling you from extracting the data. Such cases can arise due to virus infections, interruptions during downloading the ZIP file, CRC error, etc. In such situations, you should try to find and isolate the exact cause of the problem and try to download it again. However, if the problem persists then you should use a third-party ZIP repair software to repair ZIP file.

Consider a scenario wherein you are using Internet Explorer 8 on your Windows XP system, from which you download a ZIP file. However, when you try to extract the file it fails to do so. An error message is displayed, that is:

The Compressed (zipped) Folder is invalid or corrupted.”

Cause:
Such abnormal behavior may be exhibited when HTTP compression is enabled for the ZIP files from the Web server from which they are downloaded. Because of HTTP compression, the ZIP file is encrypted before it is sent to Internet Explorer. When the ZIP file is saved to your hard disk, Internet Explorer directly sends the file to the ZIP extracting application without decrypting the HTTP compression. That is why such error is raised.

Resolution:
To resolve this situation, you can perform the following workarounds:
You should try to disable the HTTP compression of the ZIP file on the Web server.
You should try to change the MIME (Multipurpose Internet Mail Extensions) type for the ZIP files on the Web server from the application/x-zip-compressed to application/octet-stream.

Now, try to download and extract the ZIP file once again, it should run fine now. However, if the issue is still not resolved then you should use a third-party ZIP recovery software to fix the problem. Such read-only tools are able to repair ZIP file without overwriting the existing data.

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