If your default apps are automatically resetting and you get 'An app default was reset' in Windows 10, here is how to resolve the notification. 

These days Windows 10 users are complaining about a new issue in which some apps set themselves as default apps by corrupting or deleting registry configuration. We recently came around this problem on our Windows 10 Pro machine.

In this case, you’ll receive a notification from Action Center saying similar statement:

An app default was reset

An app caused a problem with default app settings for .pdf files, so it was reset to Microsoft Edge.

FIX - An App Default Was Reset In Windows 10

As we said this is similar kind of statement and you can receive it for different extensions like .avi, .htm, .png etc. as well. So if the apps reset themselves to default apps, users faces inconvenience and they’ve to again set their custom app as default app for corresponding extension.

After coming around this post by a Betsy, Microsoft employee on Microsoft Community, we finally have the way to get rid of this issue.

FIX : An App Default Was Reset In Windows 10

FIX 1 – By Uninstalling Responsible Update

The post from Betsy says that Windows Update (KB 3135173) is causing this issue. It basically resets application defaults to defaults by changing registry settings or corrupting them. As Microsoft is well aware of this issue, they’re working with app providers to resolve this problem in future Windows Updates.

As of now, you can try these steps to resolve the problem:

1. Open administrative Command Prompt.

2. Type this command and press Enter key.

wusa /uninstall/ kb:3135173

FIX - An App Default Was Reset In Windows 10

After uninstalling the system, reboot and the issue will no longer persist.

FIX 2 – Set App Defaults Manually

Another alternative you can try here is to set the app defaults for the extension/format for which you’re receiving notifications. Here is how:

1. Open Settings app and go to System > Default apps.

2. In the right pane of this window, click on Choose default apps by file type link.

FIX - An App Default Was Reset In Windows 10

3. Finally, scroll down and locate the extension for which you’ve problem. Set your default app by clicking the app name next to it. Once you’re done, close the Settings app and restart your machine.

FIX - An App Default Was Reset In Windows 10

Hope this helps! If the issue still persists, try reinstalling Windows 10 without affecting your data.


  • 1. FIX 1 , personally I do not recommend . generally a KB article will fix more than one issue, so uninstall it can create a hole in the computer security .
    And anytime can be updated by an another and newer KB via update with KB uninstalled or installed or not installed
    2. FIX 2 is a double pain in the *** , because you must wait to be build a very very long list of type of files , after that you must scroll down a lot to find your file . if you have at least 3 type of files is almost suicide
    3. I prefer (is more quickly) to right click a pdf file (work with any extension)
    click properties
    click change (type of file / open with)
    and set there your option(s)
    windows 10 will keep for now your preferences
    this is working even in windows XP

  • Fix 2 doesn’t stay “fixed” anyway (Win 10 Home Basic as of May 12, 2016). Time for Linux!

  • This was all too technical for me. I don’t even understand the language. What do you mean by three types of files. I cannot even reach all my files and do not know what to do so there is no chance that I am going to right click on any of them. What is Linux? I feel absolutely desperate!!!

  • How do I discover *WHICH* APP caused the problem?
    Not seen in Event Viewer (SYS or APP), must be logged somewhere. (?)
    I’d rather discover which APP is doing this and fix the cause, not the symptom.

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