Microsoft Defender SmartScreen is a feature of the company’s Edge browser that analyses unknown files downloaded from the internet before allowing them to be run on a computer.
Though Microsoft’s scanner is normally very good at detecting internet threats, it may sometimes mistakenly mark safe programmes as threatening, such as Microsoft Edge blocks Mozilla’s Firefox browser.
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Users have reported that Microsoft Edge blocks Firefox, the popular open-source browser’s installers from the official website, according to a recent report by Techdows.
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This is said to happen while installing installers for the browser’s stable, beta, dev, and nightly versions.
On Reddit, users discovered two different instances of the Microsoft Edge blocking Firefox installer, flagging the reputable and open-source browser as potentially harmful applications.

The message “Firefox installer.exe was blocked because it could harm your device” greeted users who attempted to download the browser.
Some affected users said they successfully downloaded and installed Firefox after disabling Microsoft Defender SmartScreen.
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Although the detection of Mozilla’s browser could have been an unintentional false positive, this isn’t the first time a company has tried to discourage consumers from using a competitor’s service.
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If you’re having trouble downloading Firefox or another app from Edge, it’s not a good idea to switch off Microsoft Defender SmartScreen setting.
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Instead, use another browser to download Firefox or another app you’re having trouble downloading from Edge.
Microsoft has not yet commented on Microsoft Edge blocking Firefox.