I've been struggling with this error for hours now and I've attempted several different solutions by now, all of which include
Restarting my system, reinstalling RPH, starting with administrator perms, disabling anti-virus, forcing RPH to open GTA V in windowed mode, loading no plugins on launch, verifying integrity of GTA V game files, checking GeForce Experience to see if in-game overlay is on (which it is not). I have tried so many different solutions, none of which are working at all. I tried to reinstall LSPDFR, following the official guide shown on the website install page, making sure to follow instructions carefully. Nothing has worked so far.
I just want to play LSPDFR the first time, since I've been interested in it for years. This is a brand new computer, I know there is no issues with it being slow, and I've given it the maximum permissions I can. It is incredibly frustrating.
I am gonna attempt to do a full reinstall of GTA V and LSPDFR following the reinstall. If this doesn't work, theres gonna be no known solution and I'll probably just have to take a big fat L and just never play a mod I've wanted to play since childhood.