If Windows 10 has updated to a new version, and this version is not compatible with your actual MassCore - RTX64 runtime :
Note : this does not apply to incompatible Windows Security-Quality Updates, but to Feature-version update, e.g. Windows 10 1703 Spring Creator updated to 1709 Fall Creator.
In that case please refer to this page.
First check that there is a MassCore (RTX64 Runtime) version compatible with your updated Windows :
You will have to revert to your previous Windows version.
For a limited time after upgrading, you’ll be able to go back to your previous version of Windows by selecting the Start button, then select Settings > Update & Security > Recovery and then selecting Get started under Go back to the previous version of Windows 10.
This will keep your personal files, but it'll remove apps and drivers installed after the upgrade, as well as any changes you made to settings.
In most cases, you'll have 10 days to go back.
Go in Windows Control Panel > Programs & Features, then uninstall your current Pyramix / Ovation version and reboot your computer.
Once rebooted, uninstall the Interval Zero RTX64 X.X Runtime. If you have several Interval Zero RTX entries, please uninstall all of them before rebooting.
After the computer restart, you can now install the updated Pyramix / Ovation version, and proceed to MT Security Settings to install the updated MassCore Runtime.