Hide File Extensions not maintained since Sequoia 15.4 upgrade on M1 Mac mini and M3 MacBook Air

The answer to the question is out there on the interwebs, but I'll share what worked for me. You need to be comfortable with the command-line, using the Terminal app (I recommend iTerm2, but I digress). There is a command called defaults that lets you make changes to the system defaults, without having to dig through app settings. It does come with its own learning curve, and you can always read about with man defaults in the terminal if you want to learn more about it.

The specific setting is the global attribute AppleShowAllExtensions, which should default to false. Unfortunately it seems to be getting stuck to true even if using the Finder's settings to change it. Since the attribute defaults to false, we can just "delete" it, which the Finder sees as "use the default." The command specifies the global context with the option "-g". Once the change is made you need to restart the Finder, which is what the killall command does; you should no longer see the extensions. Don't worry, the Finder automatically restarts.

defaults delete -g AppleShowAllExtensions && killall Finder

This has been bugging me for a while, finally realized that default was the answer, which I confirmed by a quick DuckDuck search to confirm I had the correct setting.

putnik wrote:

Sequoia 15.4, files syncing to iCloud have their extensions made visible again.

At least in my setup Sequoia 15.4.1 updates Finder's Get Info "Hide extension" flag also in iCloud Drive files between different Macs as expected:

mdls image.jpg
kMDItemFSIsExtensionHidden         = 1

With Finder > Settings > Advanced > Show all file extensions OFF that file's extension is not displayed.

With Finder > Settings > Advanced > Show all file extensions ON that file's extension is displayed.

BTW some apps might reset kMDItemFSIsExtensionHidden to 0 (for example exiftool option -overwrite_original_in_place preserves it while -overwrite_original resets it to 0 -- also 'Stationary pad', hard links to the file and color label flags are reset with the latter option).

Running OS 15.5, no anti-virus or firewall. Had same problem. The finder--> settings --> advanced --> "Show all file name extensions" is unchecked (I don't want to see file extensions). In the past I was using Command-I to open the file info pane to check the "Hide Extension" box, and several minutes later the extension would re-appear. Frustrating.

Fix: Instead of using Command-I to open the pane and check the box, I instead used the long approach: I clicked once on a desktop file, then I selected "File --> Get Info" from the Finder Menu in the Menu Bar. Then I checked the Hide Extension box. The extension hid and has not returned.

Weird, but it worked for me. YMMV.

lbaker770 wrote:

My finder preference "show all file extensions" is unchecked. I have manually gone into the "info" of each file, "get info," and checked "hide extension." The extension temporarily disappears, but then later reappears.

Do you do something in between that might reset the 'kMDItemFSIsExtensionHidden = 1' flag to 0? Like copying the file to some non-Mac filesystem or cloud service that does not support that proprietary Mac metadata? Or use some 3rd party app or Terminal command that might reset it when saving the file?

iJeffR wrote:

Ever since I have upgraded to Sequoia 15.4 on both my M1 Mac mini and my M3 MacBook Air, Finder is not hiding file extensions.

I have navigated to Finder > Preferences > Advanced and toggle the "Show all filename extensions" option to off on both machines. I have also done "Get Info" on the individual files and clicked, "Hide Extensions". Then, when I come back, the extensions are back. These files are in my iCloud Drive.

You are not alone 👍

The same behaviours and same steps were performed for files synced to iCloud

Numbers files were showing the .numbers extension, Pages with the pages extension, Keynote, QuickTime Player, TextEdit files all with appended extensions

Using a M3 MBA, M2 Mac Mini and M3 Mac Mini all with Sequoia 15.4

Each was updated on the day Off Release of 15.4, Mar 31, 2025

Theses behaviours only started after the installation of 15.4 and not before

The same behaviours and same steps were performed for files synced to iCloud

Today, April 7 and as I write this reply

Just checked again and the file extensions have since disappeared ( not showing )

You may give this some time to work itself out.

Maybe a couple of days to a week

It should not be that way but patience is a virtue

apologies, I forgot a step and it won't let me edit my original post.

You can remove them by running the following command(s) in terminal. The first one installs apples Xcode command line tools and the second will remove the .jpg, .jpeg, .png, .pdf, .doc, .docx, .txt, .xlxs extensions from ALL files in your entire home folder (as long as they are not protected/locked.) The entire process took maybe 5 min once I figured it out so I wanted to share.

1. First, make sure you have Xcode command line tools installed if you dont already. You can install it by typing or copy/pasting this command into terminal and clicking enter:

xcode-select --install

2. A pop up will appear, click install.

3. Once the installation is complete, type or copy/paste the following command into terminal and click enter.

find "$HOME" \( -name "*.jpg" -o -name "*.jpeg" -o -name "*.png" -o -name "*.pdf" -o -name "*.docx" -o -name "*.doc" -o -name "*.txt" -o -name "*.psd" -o -name "*.xlsx" \) -exec SetFile -a E {} +

4. Once it is complete your file names should no longer show the extension.

FYI, if you get an error, I am not the person to ask. My computer knowledge is VERY limited and I only know how to do this because I pieced it together from a ton of different forums and tutorials, sorry!

you can run the following command in terminal and it will remove the .jpg, .jpeg, .png, .pdf, .doc, .docx, .txt, .xlxs extensions from all files in your entire home folder as long as they are not protected. took me forever to get it to work but finally had success tonight.

find "$HOME" \( -name "*.jpg" -o -name "*.jpeg" -o -name "*.png" -o -name "*.pdf" -o -name "*.docx" -o -name "*.doc" -o -name "*.txt" -o -name "*.psd" -o -name "*.xlsx" \) -exec SetFile -a E {} +

FWIW, they aren't hiding for me either.

Feel free to. send Apple a bug report.

Feedback - macOS - Apple

We understand quite well. File extensions that were hidden remained hidden. Now, after Sequoia 15.4, files syncing to iCloud have their extensions made visible again. I have reported it to Apple and I hope everybody else affected does as well.

Have you also noticed that Finder does not sort as it did before. My folders always get put on top of the list before any files, like they are not included in the sort. There has certainly been a change of some kind in the procedure.

Great suggestion.

FYI, in the future you should use the "Code Insertion" tool which has an icon on the forum editing toolbar that looks like "</>" so it is easier to read the code sections you post....it makes it easier to see the spaces & the various characters which can look nearly alike. It can also make it easier for other contributors to double check the code for any errors.

For example I copied & pasted the command in Step #3 here using the Code Insertion tool:

find "$HOME" \( -name "*.jpg" -o -name "*.jpeg" -o -name "*.png" -o -name "*.pdf" -o -name "*.docx" -o -name "*.doc" -o -name "*.txt" -o -name "*.psd" -o -name "*.xlsx" \) -exec SetFile -a E {} + 

Here is a post by @etresoft who is a well respected forum contributor & developer with the most insight into macOS. Each file has its own "hide" extension setting which is independent of the Finder's hide/show extensions.

.pages and .numbers filename extensions c… -- @etresoft explanation - Apple Community

FYI, you can easily see this in action by saving a file and making sure "Hide Extension" is not checked. That file will always show its file extension even if the Finder's overall setting is at the default of "Hide". macOS has a lot of oddities.

I noticed the same thing yesterday, and went through the usual steps as well with no luck. It has to be a bug. I'm fairly certain it will be corrected in one of the next few updates.

As I have stated elsewhere today already, Finder is not in control of hiding file extensions other than by its Get Info panel. Depending upon how the application is written, it controls whether the file extension on saved/exported documents is shown or hidden. Presently, Apple's applications (probably not all but Pages and Numbers) are designed to show the extension. Depending upon how third-party applications are written, the same is true.

Being a UNIX operating system, macOS will behave differently than Windows or Linux distributions.