I have had some problems installing hotfixes on a customers different environments, and have searched high and low on Google to try to find out the reason for the message "You cannot install the foundation (KBXXXXX) into a microsoft layer". I then ended up in here, asking this question: https://community.dynamics.com/ax/f/microsoft-dynamics-ax-forum/388988/error-when-installing-official-microsoft-hotfix-for-ax2012-r3 which were answered quite fast.
However, there was no reason for the error given, and even though I asked the one who answered me, if it had something to do with certificates, I have not received any answer to that part.
I then found this on stackoverflow:https://stackoverflow.com/questions/61660011/kb-hotfix-installation-error-in-microsoft-dynamics-ax-2012
The poster of this, then actually found out that all certificates on the individual models from any given hotfix from Microsoft made in 2019-2020 has an expiration date on 02-05-2020, I have tested this on hotfixes that were released in April 2020, and it even holds true on these. Would anyone in here be able to say if this will be corrected anytime soon???