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How to Disable the File Extension Change Warning on macOS

Published February 1, 2025 by doug

Have you ever encountered this pop-up when trying to change a file extension?

Are you sure you want to change the extension from “.txt” to “.md”?

If you make this change, your document may open in a different application.

This warning can be helpful, but if you frequently change file extensions and find it unnecessary, you can easily disable it. There are two ways to do this: via the GUI (Graphical User Interface) or the CLI (Command Line Interface).

Disable via GUI

  1. Open the Finder
  2. In the menu bar, go to Finder > Settings…
  3. Click on the Advanced tab.
  4. Uncheck “Show warning before changing an extension“

Disable via CLI (Terminal)

If you prefer using the command line, you can disable the warning using Terminal commands.

Disable the Warning

defaults write com.apple.finder "FXEnableExtensionChangeWarning" -bool "true" && killall Finder

Enable the Warning Again

defaults write com.apple.finder "FXEnableExtensionChangeWarning" -bool "true" && killall Finder

Check the Current Setting

defaults read com.apple.finder "FXEnableExtensionChangeWarning"

Reset to Default

defaults delete com.apple.finder "FXEnableExtensionChangeWarning" && killall Finder

For more defaults commands, check out: https://macos-defaults.com

Now you can change file extensions freely without interruptions! 🚀

Published in Mac

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