How To Fix Error 10661 On Mac (Easy Guide)

author avatarTodor Pichurov Hours Posted on Hours Updated on

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Ever clicked on an app only to be greeted by the frustrating 10661 error on your Mac?

This error, also known as kLSExecutableIncorrectFormat, indicates that an app’s format isn’t matching up with your Mac’s needs.

This article dives into the typical triggers of this error and offers straightforward solutions to get your applications running smoothly again.

Whether it’s updating your system, adjusting security settings, or taking deeper troubleshooting steps, we’ve got the fixes that help.

This Article Contains:

What is error code 10661 on Mac?

The 10661 error code often arises when you try to run an application that doesn’t comply with your Mac’s current settings or software requirements.

error code 10661

This error, technically known as kLSExecutableIncorrectFormat, signals that the application’s executable is in an incorrect format for your Mac, or that it is not recognized by Apple as being from an identified developer.

Additionally, compatibility issues after upgrading to the latest macOS can lead to this error.

What exactly triggers error 10661?

There are a number of potential triggers that may cause error code 10661 to appear on your screen. Some of the most common ones include:

  • Attempting to open an app that is not updated to support the latest macOS version.
  • Downloading and attempting to open a file in .exe format, which is not supported on macOS.
  • Installing software from web browsers directly, like Chrome or Safari, instead of using the App Store. This might include software that isn’t verified or recognized by Apple.
  • Running software while logged in as a guest user on the Mac, which can restrict access to necessary software permissions.

Any of these situations can lead to the 10661 error, preventing the application from launching successfully.

Understanding these common triggers can help users take preventive measures or find the right solution more efficiently.

We have an additional guide covering a large number of other common error codes on Mac that you can also explore.

How do you resolve error 10661 when opening apps?

If you encounter the 10661 error on your Mac, this typically points to a problem where an app cannot be opened due to format or compatibility issues.

Below are several steps you can take to resolve this issue you can try, assuming you are running an application that should be compatible with your system.

Verify and disk permissions on Mac

Incorrect permissions can prevent apps from launching correctly. You can check permissions to ensure that your apps have the necessary access to system files.

  1. Open the Utilities folder from your Applications folder.
  2. Launch the Disk Utility application.
  3. Select your startup disk from the sidebar.
  4. Click on the First Aid tab.
  5. Start the repair process. Disk Utility will check for permissions discrepancies and attempt to correct them.

Once the process is complete, try launching the app again to see if the error persists.

Restart your Mac to fix temporary glitches

Sometimes, simply restarting your Mac can resolve issues causing the error 10661. A restart clears temporary files and may fix underlying problems that are not immediately apparent.

  1. Click the Apple menu in the top left corner of your screen.
  2. Select the Restart option.
  3. Wait for your Mac to power off, and then turn it back on.

After your Mac restarts, attempt to open the application again.

Update macOS to eliminate compatibility issues

Running an outdated macOS might lead to compatibility issues with newer apps or updates. Ensuring your system is up-to-date is crucial for smooth operation.

  1. Click the Apple icon at the top left of your screen.
  2. Choose About This Mac.
  3. Go to the Software Update section.
  4. If an update is available, click Update Now to install the latest version of macOS.

After updating, check if the app now opens without the 10661 error.

Using SpyHunter to minimize the risk of potential errors

SpyHunter for Mac is a dedicated security tool that includes a real-time scanner and a deep detection engine.

Having an application like this can significantly lower the risk of potential malware sneaking into your Mac and causing errors similar to Error 10661 to appear.

You can download the app here and install it on your system. Perform a full malware scan from the main menu and use the interface to automatically remove any potential threats discovered.

remove malware, trojans, and other threats with spyhunter

Keeping a robust security application installed and actively protecting your Mac can do wonders for your system’s long-term health and protect against dozens of threats over time.

remove malware, viruses, and potentially unwanted programs with spyhunter for mac

Manual fixes for the stubborn 10661 error

Manual intervention often resolves this issue effectively. Let’s explore some fixes that can help restore functionality to your apps.

Remove and reinstall the problematic application

One common method to fix the error is to completely remove the application from your Mac and then reinstall it.

This process can resolve any issues caused by corrupted installation files or incomplete updates that may be causing the 10661 error. Here’s how you can do this safely:

  1. Navigate to the Applications folder.
  2. Locate the problematic app. Click and drag its icon to the Trash.
  3. To ensure all associated files are removed, open ~/Library/ in Finder (you can access this by holding the Option key while clicking on the Go menu).
  4. Search for any files or folders related to the application and delete them.
  5. Empty the Trash to permanently remove the application.
  6. Restart your Mac.
  7. Reinstall the application from the App Store or download a fresh copy from the official website.

After reinstalling, try launching the application again to see if the error persists.

Adjust your security settings to allow app installation

To prevent errors like 10661, especially when installing applications not sourced from the App Store, adjusting your Mac’s security settings might be necessary.

macOS has built-in security preferences that might block installations from unidentified developers or applications downloaded from the internet.

Here’s how to modify these settings:

  1. Open System Settings.
  2. Click on Security & Privacy.
  3. Under the General tab, look for Allow apps downloaded from
  4. You might see a lock at the bottom left of the window. Click it and enter your password to make changes.
  5. Select App Store and identified developers.
  6. If your Mac blocks an app, you will see an Open Anyway button next to the app name in this menu following an attempted installation. Click it to proceed.

By adjusting these settings, you can help ensure smoother installation of necessary applications without frequently encountering the 10661 error.

Tips to prevent future errors

Keeping your Mac running smoothly requires proactive maintenance and attentive care. Regularly updating your system and applications ensures compatibility and security, thereby mitigating the risk of encountering disruptive errors like failed app launches or system crashes.

Regular updates and maintenance practices for optimal performance

Consistency in updating your Mac is crucial. Each software update can offer enhancements, security patches, and important fixes that protect your system from vulnerabilities and improve performance. Enable automatic updates in your System Preferences to ensure you never miss a crucial patch:

  1. Open System Preferences through the Apple menu.
  2. Click on Software Update.
  3. Check the box for Automatically keep my Mac up to date.

Regular maintenance activities also play a vital role:

  • Clean up your storage space by removing old and large files.
  • Run disk utility checks to fix potential file system issues:
    • Open Disk Utility from the Utilities folder.
    • Select your startup disk.
    • Click on First Aid and then Run.
  • Monitor your Mac’s health using the Activity Monitor to shut down resource-intensive applications that aren’t necessary.

In addition to these steps, consider running a dedicated malware scanner to ensure your Mac’s environment remains secure.

By consistently practicing these maintenance tips, you’ll enhance your Mac’s performance, extend its lifespan, and reduce the likelihood of encountering significant issues that disrupt your workflow.

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author avatar

Todor has over a decade of experience in creating content about cybersecurity. He specializes in making complex security topics understandable for all. As part of the SpyHunter team, Todor uses his expertise to educate users, empowering them to better understand and manage their digital environments securely and efficiently.

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