mpkg installation fails on macOS 26.1

Metapackages were deprecated a long time ago, perhaps a decade, so it's somewhat of a surprise to me that they were working for you even that recently.

You might try secondary-clicking the .mpkg file and selecting Show Package Contents to determine if you can find any packages that can be installed.

balkrishnachoudhary wrote:

Inquiry: .mpkg Installation Failure on macOS 26.1

We're encountering a package installation failure on macOS 26.1 (Tahoe) that suggests a potential change in how the operating system handles older installer formats.

Issue Description:

An installer package (.mpkg format) is consistently failing to run on macOS 26.1. The exact error message received from the macOS Installer is:

(when running through terminal)

"This package is incompatible with this version of macOS. Contact the developer for support."

(When double clicking on .mpkg getting this prompt in 26.1)

https://discussions.apple.com/content/attachment/8cd9c80e-03ad-4aea-894b-f4e7fb179141

The exact same .mpkg file installs and runs without any issues till on macOS 26.0.

We have checked the package contents and confirmed that the installation script does not contain an explicit maximum version check that would prevent installation on macOS 26.1. The compatibility failure appears to be triggered by the Installer application itself, which leads to the following question:

Inquiry to Apple Support:

Has Apple deprecated or introduced stricter compatibility checks for Legacy Installer Packages (.mpkg or non-flat packages) in macOS 26.1 that would cause a previously working installer to fail specifically on this new OS version, even if the developer-defined version scripts permit it?

We are seeking confirmation on whether a fundamental change in the Installer framework or Gatekeeper has been implemented that now specifically rejects packages based solely on an unrecognized macOS version number, requiring developers to acquire new packages built on a macOS 26.1 SDK.

Making changes to distribute through App Store or as a pkg project will need lot of changes in the code which is planned for future  in the meantime we need to have a quick work around as this is impacting  the production users.

ref: Apple Developer Forums

Apple Support is over here—

Call Customer Support (800) MY–APPLE (800–692–7753)

or on line https://getsupport.apple.com/

or call AppleCare Support at 1-800-APLCARE (800-275-2273)

Outside the USA—Contact Apple for support and service by phone

See a list of Apple phone numbers around the world.

Contact Apple Support - Apple Support

note for developers—App Store submissions require current Xcode.

https://xcodereleases.com/ using direct downloads form the developer site(?)

some reference maybe helpful—https://www.macadmins.org/