Apple automatically instals the latest installer application on devices, allowing users to upgrade to the next major release of macOS.  The following provides a method to prevent users from running the application, ensuring administrators have the required time to prepare the business.

The provided Fileset includes an unaltered version of the Open Source Software Pashua, which is licensed under the 3-Clause BSD License.


The attached Fileset prompts users with a message, including alternate languages.  There is also allowance for control over which versions of macOS Installers are blocked.  The only requirement is the following recipe:

↓ macOS

Optionally the following Custom Field may be used to monitor the quantity of times users attempt to upgrade devices:

↓ macOS

The above instals a service using launchd.  Disassociation of the Fileset will unload this service as well as remove all files.


The Fileset is currently configured to block the 'Install macOS Big' and future versions of macOS Installer App; it would actually also stop the Beta.  Version control is managed by a plist file:


Contents of the file:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "">
<plist version="1.0">

Version of App to Block

Edit the file as required for the following:

Set to 16, which will block macOS Big Sur.  This could be lowered to block earlier (or later versions when Apple release their next major release)

Example alternatives:

Message Localisation

When the installed service blocks the App, a message is reported to the user.  Examples have been provided for English and German.

The language is determined by the first two characters from the following command:

$ defaults read -g AppleLanguages | awk -F "\"" '/\"/ {print $2; exit}'

As such en-GB, en-US, en-AU, etc will all result in an English version.

Language template files are stored in the path:


English and German respectively:

Copy and edit the files appropriately for additional languages.

Example to add French

User has French language set:

$ defaults read -g AppleLanguages | awk -F "\"" '/\"/ {print $2; exit}'

Based upon this, create a copy warning file (note the suffix '_fr'):

Edit '*.title' and default message 'txt1.default' appropriately:

# Set window title
*.title = Installation bloquée

# Introductory text
txt.type = text
txt.default = macOS Installer Application
txt.height = 100
txt.width = 310
txt.x = 100
txt.y = 120

txt1.type = text
txt1.default = Cette version de macOS n'est pas prête pour l'environnement de production. Veuillez contacter le service informatique si nécessaire.
txt1.height = 100
txt1.width = 310
txt1.x = 100
txt1.y = 50

img.type = image
img.x = 20
img.y = 70
img.maxwidth = 64
img.path = /usr/local/etc/FileWave_Icon.png

Text content will impact the view.  Consider changing height, x and y values if the view does not appear as intended.

Upload and replace the 'img.path' as your own company logo for customisation.