Installer packages are failing to install on macOS26.1

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Created 2d

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Hi, We use Flat package installers (.pkg based installers) to install our applications on macOS. In macOS 26.1, installation is failing with the error

Unable to use PK session due to incompatible packages. Terminating. 2025-11-03 14:22:36+05:30 Admin-3 installer[1160]: Install failed: The Installer could not install the software because there was no software found to install.

Same installer package is working on macOS 26.

Any help is greatly appreciated.

Answered by DTS Engineer in 864785022

Is this only affecting new versions of your product? Or are you seeing it with old versions? That is, if you take a version of your product built, say, 6 months ago and try to install it on macOS 26.0 and macOS 26.1, do you still see it work on the former and fail on the latter?

If so, you should file a bug about that, making sure to include:

A copy of the installer package
A sysdiagnose log taken shortly after seeing the failure

Once you’re done, please post your bug number.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

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Answer 1

DTS Engineer OP

Apple

1d

Recommended

Is this only affecting new versions of your product? Or are you seeing it with old versions? That is, if you take a version of your product built, say, 6 months ago and try to install it on macOS 26.0 and macOS 26.1, do you still see it work on the former and fail on the latter?

If so, you should file a bug about that, making sure to include:

A copy of the installer package
A sysdiagnose log taken shortly after seeing the failure

Once you’re done, please post your bug number.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

0

Answer 2

premak OP

1d

Hi,

Thank you for the reply.

Yes, it is affecting the older version of the product which was released few months back. New and older version of the product works on macOS 26. Our software was working on beta version of the macOS 26.1 as well.

Bug id is: FB20929578

Regards Prema Kumar

0

Answer 3

premak OP

17h

Hi,

Installation was working on build version 25B5042K.

regards

Prema Kumar

0

Answer 4

DTS Engineer OP

Apple

13h

Bug id is: FB20929578

Thanks.

I looked at your bug and, while there’s a sysdiagnose and a system profile, I can’t see a copy of your installer package. Did you attach it? If not, please do.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

0

Answer 5

premak OP

12h

Hi,

In the bug description, I have mentioned a link to download our package.

Please let me if that is not part of the message.

regards

Prema Kumar

0