Installing the monthly Windchill critical patch set should not break other PTC provided products and functionality.
Two specific "products" come to mind - ThingWorx (PTC Navigate) and the Windchill Performance Advisor. Both of these require a patch to be applied to the Windchill server(s) during their initial installation. Both of these installations break every time a new CPS is installed. Having to reinstall these products every time a CPS is installed is adding an extra 30 minutes of downtime per server per month. For 24/7 global operations, those minutes matter.
This behavior seems to directly contradict the information provided about the nature of critical patch sets. From CS134275:
How will applying CPS releases affect customizations ?
Customizations that follow PTC best practices using supported API’s should not be impacted by CPS releases.
Changes delivered via CPS should not alter the behavior of supported and properly functioning API’s.
Customizations that follow supported techniques should not require refactoring.
It would seem that PTC's own internal developers are not following their own best practices for software development...
The "how to" guide for installing the critical patch sets also makes no mention of needing to reapply other pre-existing patches. (No step 13b.) From CS149102:
12. Click Install to install the CPS
13. Make sure that the installation completed successfully
14. Start Apache / HTTPServer
It would probably be good to update this guide so others don't spend days working with tech support trying to figure out why things are suddenly broken...
PTC, please adjust how the critical patch sets are built and deployed so they don't keep breaking other functionality. Thanks!