What is Error 79 – Inappropriate File Type or Format

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Error 79 Inappropriate File Type or Format

Do you need to send 10 to 20 images as an attachment via email? Well, that is possible. Just attach the images directly and wait.

However, the process is often time-consuming, especially if large files are involved. To make sending multiple files or images easier and more convenient, add all of them to a ZIP file and send it.

What is a ZIP File?

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A ZIP is an archive file format that allows lossless data compression. Simply said, it is a collection of one or more folders or files, compressed into one file.

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Zip files are often used to store and share software, documents, images, videos and other types of digital data. The name “ZIP” comes from the word “compress,” which refers to the process that reduces the size of a file by removing unnecessary or redundant data.

To create a zip file, you need an archive utility such as WinZip or 7-zip. When you unzip files on your computer, it may look like one long list with different types of files in it. This is because when you unzip file (or extract) all the contents from the compressed archive, they will be restored into their original individual folders for easy access.

You can also use .ZIP extension to send email attachments that are larger than what your email provider allows for sending attachments without getting them rejected because they exceed the maximum attachment size limit.

Although the ZIP file format is popular on Windows devices, it is actually supported on Macs. The only problem is that some Mac users encounter errors with it.

One of the most notorious errors associated with ZIP files on Macs is the error 79 – inappropriate file type or format. What is this error all about? Will it affect an app, folder, user account, or software on your Mac Catalina device? Read on.

What Is Error 79 on Macs?

Cannot unzip files on your Mac because of error 79? Relax. You are not alone. Some Mac OS users have also been complaining that they were unable to expand or unzip ZIP files on their computers because of this annoying error.

According to them, it surfaces whenever they double-click on a file they want to unzip. The error code even comes with the error message “Unable to expand filename.zip (Error 1 – Operation not permitted.”

But what triggers the error to appear? Well, there are many possible reasons. We’ve listed a few of them below:

  • Damaged download file – Did you download the file via a web browser? There is a chance that the ZIP file you’re trying to open is damaged. You might have closed the website before the download process was even completed. So, when you try to unzip it, error 79 appears. In this case, the best solution is to download the file again and make sure you down close the website right away.
  • Large files contained in the ZIP file – Another possible reason why the error 79 appears is that the file you are trying to unzip contains a very large file. Because your Mac’s Archive utility doesn’t allow you to decompress or unzip large files, it shows the error message instead. To resolve this, you need to use the Terminal utility to decompress the ZIP file.
  • Permission issues – Sometimes, permission issues trigger the error 79 to show. The ZIP file’s directory might have been set with limited read/write permissions, keeping you from accessing its contents. To fix this, you will need a third-party tool.
  • System junk – There are instances when system junk meddles with important system processes, causing error codes to pop up at random.

Now that you know what causes this error, how do you resolve it?

How to Fix the Error 79 on Your Mac

Unable to unzip file on MacOS? Below are more detailed solutions on how to successfully fix error 79 on your Mac:

Solution #1: Download the ZIP file again

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As mentioned above, the error 79 may surface if the file you are trying to open is damaged. To solve this, just download the file again, making sure you don’t close the website you’re downloading the file from.

Solution #2: Unzip the file by using the Terminal utility

If double-clicking on the ZIP file does not work and you are still unable to unzip the file, try doing it using Terminal. By default, it is the built-in Archive utility that decompresses ZIP files. When it’s not able to decompress them due to size limitations, it throws the error 79. And in this case, you need to decompress the file in Terminal.

Many macOS Catalina users have tried this fix, and it worked for them. So, it’s worth trying on your end, too. Here’s how:

  1. Press and hold down the Command and Space keys to launch Spotlight.
  2. Into the text field, input Terminal.
  3. Hit Enter. This will open the Terminal utility.
  4. Next, execute the unzip command to unzip. Into the command line, enter this command: unzip filename.zip
  5. Press Enter. Wait as Terminal decompresses the file.

Solution #3: Scan your system

The sad truth is that junk files accumulate on your Mac without you knowing. As you surf the web or even do nothing, cache and unnecessary files are generated, taking up valuable system space and impacting system efficiency.

Free your Mac from all sorts of junk that cause problems like error 79 to occur. Scan it with a Mac repair tool.


Every day we are confronted with potential data breaches, malware attacks, and other cyber events. To protect yourself from these threats, you should always use .ZIP extension to store your sensitive data on your account.

Though ZIP files are extremely handy, especially if you need to send multiple files via email, you should know that issues are also inevitable. The best way to get through issues like error 79 in the future is to simply be familiar with the solutions we have presented above.

First, you may try to download the program or software once again. Make sure you don’t close the source site to ensure the download completes.

If it does not work, use the Terminal utility. Execute the unzip command and wait for the process to complete.

Finally, scan your system. It is possible that unwanted programs and app exist on your current Catalina user account. Getting rid of them could resolve the problem in some cases.

Have any of the solutions helped resolve the error 79 on your Mac? Do you have any comments about this article? Let us hear you and your experience in the comments!

2 thoughts on “What is Error 79 – Inappropriate File Type or Format
  1. Tomas
    September 20, 2021, 9:17 PM

    Thank you very much for help!!

  2. Tomas
    September 20, 2021, 9:18 PM

    Thank you very much for help!! You’re only one, that helped me!

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