How To Unzip A CPGZ File on Mac

Evan Gower May 11, 2021

For those who are having issues with opening a zip file and converting it to a CPGZ file on macOS, we have a guide to help learn how to unzip a CPGZ file. For those who ask what is a CPGZ file, CPGZ is a compressed archive that combines the Copy In, Copy Out archive format, and GZIP compression. A CPGZ file is similar to a TGZ file that uses a GZIP compression and TAR container on macOS.

When Mac users try to open a zip file and convert it to a CPGZ file, there are several issues that can happen. Sometimes, when the ZIP file is unzipped, it converts to a CPGZ file, and when Archive Utility is launched the file turns back to a ZIP file. This process continues in a loop, making it almost impossible to unzip a CPGZ file on your Mac. Below are some of the reasons that this happens and how to fix these issues as well.

Why is a File in CPGZ Format?

There are several possible reasons that your file is in the CPGZ format:

Some web browsers don’t correctly download the file
Incomplete download
Corrupted file

These files are characterized by a looping process where you double-click on the file but it only creates a new zipped file. You could spend hours clicking on the document, but it will never open for you.

How to Unzip a CPGZ File

There are a lot of complaints online and in forums about users’ inability to unzip this type of file. If you’re experiencing this problem you aren’t alone, and fortunately there are various solutions.

Download the File Again With a Different Browser

Some web browsers don’t correctly download the original file, and it may work using a different browser like Safari, Google Chrome, or Firefox. Generally, this will fix the solution, as the file was not downloaded correctly, thus causing these issues.

There are also two other methods that should help fix this issue and can be found below. If downloading from another web browser isn’t effective, or it isn’t an option keep reading.

Install & Use The Unarchiver

Another option is to download and install The Unarchiver. This is a third-party app that is great for compression formats and is used to archive any file format. The Unarchiver is similar to the standard default Archive Utility found on Mac OS Sierra. This tool is great for fixing the ZIP/CPGZ file problems on Mac OS Sierra.

Download and install The Unarchiver.
Locate the document you’re having trouble with
Click ‘File’ in the upper right-hand corner of your screen
Click ‘Get Info’ to access the menu
Choose ‘Unarchiver’ in the ‘Open With’ menu
Open the .zip or .cpgz file that you’re having issues with using The Unarchiver and let it decompress.

Unzip from the Command Line

If the two methods from above don’t work, a third option to unzip a CPGZ file on Mac OS X is to use the command line unzip tool. Generally, this is used to break archives out of the .zip to .cpgz cycle. The steps below will show you how to do this for the original .zip archive:

Turn on your Apple computer.
Open Terminal. You can find it in the ‘Utilities’ folder, under Applications.
Find the .zip file in the Finder.
At the command line, type “unzip” followed by a space.
Drag and drop the .cpgz or .zip file into the Terminal window and hit enter. You could type out the location of the file in the command terminal but the drag and drop method will automatically populate this information.

Open Finder and click on ‘Applications’ on the left-hand side to access the command terminal.

The command-line method generally works the majority of the time to fix the issue and unzip a CPGZ file on Mac OS X. While the simplest solution would be to download the file again using a different browser and the unzipping process should work correctly, it’s still helpful to know that there are other options, especially if trying to use a different browser doesn’t correct the issue.