@Terry-R said in Upgrade application when both bits application installed on single machine:
it seems that the knowledge of which plug-ins are available is directly from the program files folder for each NPP folder. Is that correct as you see it?
Yes. My recollection is that on startup, Notepad++ will look for a plugins folder in the same folder as the executable; it will then enumerate folders within the plugins folder, then check each folder for a dll with the same name as the folder. It will then attempt to load those dlls and make some calls to specific entry points in those dlls that must proceed as expected to register the plugin (else a message about an invalid plugin will be shown).
There was some discussion in this forum — I think not too long ago — about the possibility of individual users in a multi-user environment being able to enable or disable individual plugins, with the ability to install plugins still being limited to administrators; but that proposal was never pursued.