I'm happy I came across this because I ran into this for the first time today.
We recently upgraded to WGM12.1.1.0 for our NX while still on Creo 4. The WGM version installed Creo Platform Services 9 with it's appropriate Creo Agent version. The WGM worked just fine as did Creo4 (with separate cache locations enforced through ENV variables for WGM and through .psf files for the Creo configurations).
I then upgraded to Creo 8.0.6.0 which installs Creo Platform Services 8.
There's a compatibility matrix of sorts (CS302660) and there's this bit about incompatibility:
Note: If multiple installations of Creo and/or WWGM products are installed on the same client machine, Creo Platform Services 4, 5, 6, 7, 8 or 9 will be installed during the first product installation to the default installation location for the respective product and subsequently installed products will either reuse or update the previous Platform Services installation with a later release (if the installer contains a later release)
Creo Platform Agent may result incompatible for either Creo Parametric or the WWGM and its location should be explicitly set with the environment variable CREO_AGENT_EXE_PATH, see article CS292414
In CS292414 it says that if there are incompatible versions of Platform services between Creo and WGM you need to separate out pointers to the correct creoagent.exe with environment variables using CREO_AGENT_EXE_PATH. It also points out that by default there's only one common installation of the Creo Agent by default (C:\Program Files\Common Files\PTC\Creo\Agent).
Since I installed WGM12.1.1.0 first (and got Creo 9 Platform Services) and then installed Creo 8 after, everything seemed to work with the single creoagent.exe. There are 2 Platform folders in the Creo folder Platform\8 and Platform\9 with a single Agent folder that has the creoagent.exe. That implies Creo8 reused the Creo 9 Platform services agent and is compatible with it.
I did in fact install separately the Creo 8 and Creo 9 platform services so that there is a creoagent.exe in C:\Program Files\Common Files\PTC\Creo\Agent for the WGM to point to and a separate one (Creo 😎 in C:\Program Files\PTC\Creo\Agent. It was when I used CREO_AGENT_EXE_PATH to point to the correct agents that both Creo 8.0.6.0 and WGM12.1.1.0 stopped working with the error from @VladimirN (cs353816 ) and also this one (CS182686 ). For that second one, I did end up having to uninstall everything, clean up the registry and reinstall.
Has anyone used the CREO_AGENT_EXE_PATH variable successfully? How far apart were the versions of platform services? Is there a true compatibility matrix that shows which agent version is NOT compatible with which version of Creo and WGM?
I'm thinking it may be best to stick with software versions that share compatibility with the platform services.
