I recently experienced the "Invalid plugin detected" error while trying to open PDFs directly from my desktop, so there is no browser involved. I uninstalled and reinstalled Reader DC but I still get the same error, even when opening the program without trying to open a PDF. I have also rebooted the system since reinstalling, but no joy.
I am running Windows 10 version 1909 Home on a Ryzen 9 3900X with 32GB RAM. Would installing the version 2004 update for Windows fix this issue?