All About Fix Cannot Set a Default App For MP4 on Windows 11/10

All About Fix Cannot Set a Default App For MP4 on Windows 11/10

MP4 is one of the most commonly used video file formats for digital media viewing. Whether it’s watching your favorite movie or sharing a video with friends, MP4 has become an essential part of our daily lives. However, many Windows 11 and 10 users have faced the frustrating issue of not being able to set a default app for MP4 files. This problem can cause inconvenience and hinder the smooth functioning of your digital media viewing experience. In this article, we will discuss the reasons behind this issue and provide effective solutions to fix cannot set a default app for MP4 on Windows 11/10. So, if you are facing this problem, read on to learn how to resolve it and enhance your MP4 viewing experience.

Fix: Cannot Set a Default App For MP4 on Windows 11/10

Many Windows 11/10 users have reported an issue where they are unable to set a default app for MP4 files. This can be frustrating as MP4 is a popular video format and not being able to set a default app means that every time they try to open an MP4 file, they have to manually choose the app they want to use. If you are facing a similar issue, don’t worry, as there are a few solutions that can help you fix this problem.

Solution 1: Change Default App Settings

The first solution is to change the default app settings in the Windows Settings app. Here’s how to do it:

1. Open the Windows Settings app by pressing the Windows + I keys on your keyboard.

2. Click on “Apps” and then select “Default apps” on the left-hand side.

3. Scroll down and click on “Choose default apps by file type.”

4. Wait for the list to load and then scroll down until you find .mp4 in the list.

5. Click on the current default app (which may be “Films & TV” or “Movies & TV”) and select the app you want to use as the default for MP4 files.

6. Close the Settings app and try opening an MP4 file to see if the issue has been resolved.

Solution 2: Change Default App in File Explorer

If Solution 1 did not work, you can try changing the default app for MP4 files directly in File Explorer.

1. Open File Explorer by pressing the Windows + E keys on your keyboard.

2. Navigate to any folder that contains an MP4 file.

3. Right-click on an MP4 file and select “Open with” > “Choose another app.”

4. Select the app you want to use and check the box for “Always use this app to open .mp4 files.”

5. Click on “OK” to save the changes.

Solution 3: Update or Reinstall the App

If the above solutions did not work, the issue could be with the app itself. Try updating the app to the latest version or reinstalling it from the Microsoft Store. Once the app has been updated or reinstalled, try setting it as the default app for MP4 files again.

Solution 4: Reset File Associations

If none of the above solutions work, you can try resetting file associations for MP4 files. Here’s how to do it:

1. Open the Command Prompt as an admin by right-clicking on the Start button and selecting “Windows PowerShell (Admin).”

2. In the Command Prompt, type in the following command and press Enter:

dism.exe /online /cleanup-image /restorehealth

3. Wait for the process to complete and then restart your computer.

4. After the restart, try setting a default app for MP4 files using Solution 1 or Solution 2.


One of these solutions should help you fix the issue of not being able to set a default app for MP4 files on Windows 11/10. If the problem persists, it could be a sign of a larger issue with your operating system. It is recommended to perform a system scan for any errors using a trusted PC optimization software, and if necessary, contact Microsoft support for further assistance.

1. Reset the Movies & TV App

The Movies & TV app is a popular media player and video streaming application that comes pre-installed on Windows 10 devices. It allows users to play and stream movies and TV shows from their personal collections and the Microsoft Store. However, like any other software, the Movies & TV app may encounter issues that require troubleshooting. One common solution is resetting the app, which can help resolve any performance or playback problems.

Here’s how you can reset the Movies & TV app on your Windows 10 device:

Step 1: Open the Settings app by clicking on the Windows Start menu and selecting the gear icon.

Step 2: In the Settings menu, click on the “Apps” option.

Step 3: Under the Apps & features section, find the “Movies & TV” app and click on it.

Step 4: A new page will open with options to Modify, Uninstall, or Advanced options. Click on the “Advanced options” link.

Step 5: On the Advanced options page, scroll down until you find the Reset section.

Step 6: Click on the “Reset” button. A pop-up window will appear, asking you to confirm if you want to reset the app.

Step 7: Click on the “Reset” button in the pop-up window to confirm your choice. The app will begin to reset, which may take a few minutes.

Step 8: Once the reset is complete, you’ll see a message that says, “This app has been reset. You may now close this window.”

Step 9: Close the Settings app, launch the Movies & TV app, and check if the issues have been resolved.

The reset process will delete all the app’s data, including preferences, settings, and any stored information. It’s like installing the app again from scratch, but without going through the actual installation, downloading, and updating process.

Resetting the Movies & TV app may help fix various issues, such as crashing, freezing, or playback errors. It can also help if the app is not displaying content correctly or if there are audio and subtitle sync problems. However, if the issue persists after resetting the app, you can try other troubleshooting steps, such as updating your graphics drivers, checking for Windows updates, or reinstalling the app.

In conclusion, the Movies & TV app offers a convenient and easy way to watch your favorite movies and TV shows on your Windows 10 device. However, if you encounter any problems while using the app, a simple reset may be all you need to get it back up and running smoothly. So, the next time you face any issues with the Movies & TV app, try resetting it using the steps mentioned above, and hopefully, it will solve the problem.

2. Install the Missing File Extensions

2. Install the Missing File Extensions

File extensions are an integral part of every file we use on our computers. They define the type of file and tell the computer which program to use to open it. However, there are times when we come across files with missing extensions, making it difficult for our computers to recognize and open them. In this blog post, we will discuss how to install missing file extensions and ensure a seamless computing experience.

Step 1: Identify the missing file extension

The first step in installing a missing file extension is to identify the type of file it is. For example, a Word document will have a .docx extension, while an image will have a .jpeg or .png extension. This can be done by right-clicking on the file and selecting “Properties” or “Get Info” on a Mac. The file extension will be listed next to the file name.

Step 2: Download the necessary software

Once you have identified the file extension, the next step is to download the necessary software to open the file. Most file extensions have specific programs associated with them. For example, a .docx file can be opened with Microsoft Word. If you do not have the necessary software, you can download it from the internet or purchase it.

Step 3: Install the software

After downloading the necessary software, follow the prompts to install it on your computer. This may involve accepting terms and conditions, choosing an installation location, and creating desktop shortcuts. Once the software is installed, make sure to restart your computer to ensure the changes take effect.

Step 4: Change the file extension

If the file you are trying to open has a missing extension, you can manually change it by renaming the file. Right-click on the file, select “Rename,” and replace the missing extension with the correct one. Make sure to type it exactly as it should be, including the dot before the extension.

Step 5: Test the file

Now that you have installed the necessary software and changed the file extension, try opening the file again. If the software was the missing piece, the file should open without any issues. If not, try changing the file extension to a different one and see if it works with another program.

Step 6: Use a file recovery tool

If changing the file extension does not work, it is possible that the file is corrupted. In this case, you can use a file recovery tool to repair the file. There are many free and paid options available online, so choose one that best suits your needs.

In conclusion, installing missing file extensions is an easy process that can be done in a few simple steps. It is essential to have the correct software for opening the file and rename the file with the correct extension. This ensures a smooth computing experience and saves you from the hassle of dealing with unrecognized files.

3. Downgrade to Windows 10

As Microsoft continues to release new versions of their operating system, many users are tempted to upgrade in order to take advantage of the latest features and improvements. However, upgrades don’t always go as planned and some users may find that they prefer an older version of Windows. In these cases, downgrading to Windows 10 may be the best option.

1. Create a Backup
Before starting the downgrade process, it is important to create a backup of all important files and data. This will ensure that if anything goes wrong during the downgrade, you won’t lose any important information.

2. Check System Requirements
Before downgrading to Windows 10, make sure your computer meets the system requirements for the operating system. This includes having at least 1GHz processor, 1GB RAM (32-bit) or 2GB RAM (64-bit), and 20GB of free hard drive space.

3. Download Windows 10 ISO
In order to downgrade to Windows 10, you will need to download a Windows 10 ISO file. This can be found on the Microsoft website or through a simple Google search. Make sure to download the correct version for your computer (32-bit or 64-bit).

4. Backup Drivers
Before downgrading, it is recommended to backup your current drivers in case any hardware issues arise. This can be done through a third-party software or through Windows’ built-in backup tools.

5. Create a Bootable USB Drive or DVD
Once the ISO file is downloaded and the drivers are backed up, you will need to create a bootable USB drive or DVD with the Windows 10 ISO file. This can be done through various free software such as Rufus or Microsoft’s Media Creation Tool.

6. Backup Product Key
In order to activate Windows 10 after downgrading, you will need your product key. This can usually be found on a sticker attached to your computer or through a software such as Belarc Advisor.

7. Start the Downgrade Process
Insert the bootable USB drive or DVD into your computer and restart it. You may need to change the boot order in BIOS settings to boot from the external drive. The Windows 10 installation process will then begin.

8. Follow On-Screen Instructions
During the installation process, you will be prompted to choose between an upgrade or custom installation. Select custom installation and then select the partition where your current Windows version is installed. This will overwrite the current operating system with Windows 10.

9. Activate Windows 10
After the installation is complete, you will need to activate Windows 10 using your product key. If you don’t have your product key, you can use a Windows 7 or 8 product key to activate Windows 10.

10. Restore Files and Drivers
Once you have successfully downgraded to Windows 10, you can restore your files and drivers from the backup you created in step 1.

In conclusion, downgrading to Windows 10 may be a good option for those who prefer an older version of Windows or have encountered issues with a newer version. However, it is important to note that downgrading is not always possible and may cause some compatibility issues. It is always recommended to do thorough research and carefully consider the pros and cons before making a decision to downgrade.


In conclusion, setting a default app for MP4 files on Windows 11/10 can be a simple and straightforward process with the right steps and knowledge. It is important to make sure that the selected app is compatible and suitable for handling MP4 files to avoid any issues. In case you encounter difficulties in setting a default app, following the troubleshooting tips and contacting technical support can help resolve the problem. Keeping these steps in mind can help enhance your overall experience in using MP4 files on Windows 11/10. With these tips, you can easily fix the issue of not being able to set a default app for MP4 files and enjoy seamless playback and management of your media.

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