Turn off the extension-change warning in Finder

The confirmation Finder throws whenever you edit a file's extension is a Finder setting, so the cleanest place to turn it off is Finder's own Settings window. It lives on the Advanced tab as one checkbox: Show warning before changing an extension. Uncheck it and the dialog is gone — with a Terminal equivalent below if you prefer that.

Where the setting lives

Finder Settings is easy to miss because it belongs to Finder, not to System Settings. Make sure Finder is the active app first — click the desktop or any Finder window — then:

1. Open the Finder menu in the menu bar and choose Settings…, or just press Cmd+,.
2. Click the Advanced tab (the gear icon, far right of the four tabs).
3. Uncheck Show warning before changing an extension.

There is no Save button — the change sticks the moment you uncheck it, and Finder stops warning you immediately. To put the safeguard back, return here and tick the box again. The tab and its wording are identical on macOS 13 Ventura, 14 Sonoma, and 15 Sequoia.

What else is on the Advanced tab

While you are here, the Advanced tab collects several of Finder's most useful switches, and they pair well with the one you just changed:

• Show all filename extensions — reveals extensions on every file, so you can actually see what you are editing.
• Show warning before removing from iCloud Drive — the iCloud cousin of the extension warning.
• Keep folders on top — sorts folders above files in every window.
• When performing a search — controls whether search starts in the current folder or the whole Mac.

Each is a self-contained toggle you can flip without affecting the others.

The Terminal equivalent

That checkbox maps to one Finder preference key, which you can set directly:

# turn the extension-change warning off
defaults write com.apple.finder FXEnableExtensionChangeWarning -bool false
killall Finder

# undo: turn it back on
defaults write com.apple.finder FXEnableExtensionChangeWarning -bool true
killall Finder

killall Finder restarts Finder so the new value takes hold; open windows reopen by themselves. The command and the checkbox are two views of the same setting — change it in one place and the other reflects it.

The warning worth understanding

Before you leave it off for good, know what the dialog was protecting: renaming an extension changes the label, not the file. If you want the reasoning and the cases where it still matters, read the fuller take on the 'Change the extension?' warning.