Here is comprehensive content about in the context of Windows Installer (MSI) .
If you maintain an IsScript MSI, consider modern alternatives: isscript msi
Open the MSI → CustomAction table → Filter Type column for 1 (DLL) and Target containing ISScript . Here is comprehensive content about in the context
Scripted custom action expects UI mode but msiexec /x /qn runs silent. Fix: Use Is(UNINST_UI) guards in script. isscript msi