Mrsuperx13

go to and open Grand Theft Auto V\lspdfr\lspdfr.ini and change Ambient.DisableEscapedSuspectEncounter = false to Ambient.DisableEscapedSuspectEncounter = true

the configuration files can be found in Grand Theft Auto V\plugins\LSPDFR\UltimateBackup
they are called DefaultRegions.xml and CustomRegions.xml. 
and this would be an example of how you would place it in a vehicle entry line
<Vehicle chance="24" livery="1" pax="1" pax_chance="40">POLICE</Vehicle>
you would simply change the number for the livery modifier depending on which livery you would like to spawn.

Dude. The vehicles.rpf does belong there. It's a different patchday than the one you have sent him to, and is currently in the mods folder. Much simpler because it's empty and uses the old convention of a vehicles.rpf instead of the system they have implemented in mp2023_02. 
Do you have any other mods installed in the mods folder that you can confirm are working?
Because right now it would seem like your mods folder is not being read properly.

Issues solved off site. User had another DLC pack installed overriding all installed vehicles - it wasn't vanilla vehicles showing up in game but lore friendly ones that the user assumed were vanilla.

I don't really understand what this sentence means.
There are two options for loading the game:
1. Launching the regular GTA through whichever launcher you own it on.
2. Launching RPH and letting it launch and hook GTA automatically.
 
I presume you are talking about the second option?
Once in game (with RPH hooked) you can open the RPH console by pressing F4 (by default) and typing "LoadPlugin LS" It will then give you options to auto complete the rest of the command to load lspdfr.
The other option is to select which plugins to load through the RPH settings menu. You can access this by pressing and holding the Left Shift button when launching RPH. 

You can thank @Mrsuperx13. Faulty gameconfig led to ELS/trainer not loading.

Presumably because you accidentally replaced the cars lighbar textures. Reinstall the original car files

In `GTA/LSPDFR/lspdfr.ini` change `Main.DisableGameBlipHiding = false` to `Main.DisableGameBlipHiding = true`

Apologies - didn't notice that. Moved.

Something is interfering with RPH I'd recommend cleaning your game folder and starting again.
 

You are missing the CalloutInterfaceAPI.dll file. 
reinstall it from one of the plugins that requires it for example SuperCallouts

You are running an old version of lspdfr.
Update LSPDFR/RPH https://bit.ly/3A9CIhX 
DOWNLOAD THE "MANUAL INSTALL" VERSION, copy and paste EVERYTHING in the zip except for the licenses and lspdfr folders (you can ignore them) into your main GTA directory.

This is simply not true. 
SHV and ELS are 100% stable. The only time they may cause crashes is through user error or windows interfering with them. 
Furthermore if you had an issue with ELS... That would reflect on ELS not on SHV.

You are running an old version of lspdfr.
Update LSPDFR/RPH https://bit.ly/3A9CIhX 
DOWNLOAD THE "MANUAL INSTALL" VERSION, copy and paste EVERYTHING in the zip except for the licenses and lspdfr folders (you can ignore them) into your main GTA directory.

You are running an old version of lspdfr.
Update LSPDFR/RPH https://bit.ly/3A9CIhX 
DOWNLOAD THE "MANUAL INSTALL" VERSION, copy and paste EVERYTHING in the zip except for the licenses and lspdfr folders (you can ignore them) into your main GTA directory.

You are running an old version of lspdfr.
Update LSPDFR/RPH https://bit.ly/3A9CIhX 
DOWNLOAD THE "MANUAL INSTALL" VERSION, copy and paste EVERYTHING in the zip except for the licenses and lspdfr folders (you can ignore them) into your main GTA directory.

This is simply not true. 
SHV and ELS are 100% stable. The only time they may cause crashes is through user error or windows interfering with them. 
Furthermore if you had an issue with ELS... That would reflect on ELS not on SHV.

To 
 
To add to this and @Mrsuperx13's incredibly informative response; the SlimDX issue is a system-specific error.
Meaning that yes; it's an exception caused in RPH by your system.
 
The Antivirus scheme + the reinstallation of DX and system specific drivers has always seemed to work best.
It's not RPH, LSPD:FR or your mods. It's your system. And that is why it's so hard to diagnose. 
Everyone's system is different.
 
Therefor, please retry the steps in the RPH FAQ like mentioned above. 
As said all the way back in 2020:

Try renaming your mods folder to _mods
Then try start your game again.

If you installed mod files in the mods folder, like has been recommended for years now, this is literally impossible.
1. (I know it was tongue in cheek but) Rage stands for Rockstar.Advanced.Game.Engine ("plugin hook" is pretty self explanatory) the game engine that Rockstar created and that runs GTA.
2. It is no one in the community's fault that Rockstar are completely anti-modding and have constantly tried to shutdown mod creators and mod access at every opportunity they can. 
3. In that regard it makes sense why GTA V is worse than GTA IV - Rockstar have gotten more advanced and more anti-mod.
4. Everything we have in terms of modding Rockstar games is because amazing talented people have found smart workarounds to all the roadblocks Rockstar have put in place. 
 
This community is filled with amazing people who have dedicated so much time and effort for free to help ungrateful people like you time and time again.
Do you know why any of those troubleshooting steps are known? Because people like A Stranger (Head of the RPH discord and creator of the RPH faq(which has every known possible solution to the SlimDX error for example)), and many others, have spent years of their lives, thousands of hours of their free time, dedicated to helping people and finding solutions to the problems that come along with modding a game that does not want to be modded. 
 
I'm sure it's frustrating to try and solve such an annoying issue when you just wanna play the game. But don't take it out on the people who are the ones that are literally trying to help and have laid the groundwork for every troubleshooting step you have tried so far for this issue and every other known issue. 
 
In conclusion double check the RPH FAQ double check every step as everything known about that error is documented there.
 
P.s. when dealing with problems it's always good to be specific - For GTA V it's called LSDPFR not LCPDFR

If you installed mod files in the mods folder, like has been recommended for years now, this is literally impossible.
1. (I know it was tongue in cheek but) Rage stands for Rockstar.Advanced.Game.Engine ("plugin hook" is pretty self explanatory) the game engine that Rockstar created and that runs GTA.
2. It is no one in the community's fault that Rockstar are completely anti-modding and have constantly tried to shutdown mod creators and mod access at every opportunity they can. 
3. In that regard it makes sense why GTA V is worse than GTA IV - Rockstar have gotten more advanced and more anti-mod.
4. Everything we have in terms of modding Rockstar games is because amazing talented people have found smart workarounds to all the roadblocks Rockstar have put in place. 
 
This community is filled with amazing people who have dedicated so much time and effort for free to help ungrateful people like you time and time again.
Do you know why any of those troubleshooting steps are known? Because people like A Stranger (Head of the RPH discord and creator of the RPH faq(which has every known possible solution to the SlimDX error for example)), and many others, have spent years of their lives, thousands of hours of their free time, dedicated to helping people and finding solutions to the problems that come along with modding a game that does not want to be modded. 
 
I'm sure it's frustrating to try and solve such an annoying issue when you just wanna play the game. But don't take it out on the people who are the ones that are literally trying to help and have laid the groundwork for every troubleshooting step you have tried so far for this issue and every other known issue. 
 
In conclusion double check the RPH FAQ double check every step as everything known about that error is documented there.
 
P.s. when dealing with problems it's always good to be specific - For GTA V it's called LSDPFR not LCPDFR

If you installed mod files in the mods folder, like has been recommended for years now, this is literally impossible.
1. (I know it was tongue in cheek but) Rage stands for Rockstar.Advanced.Game.Engine ("plugin hook" is pretty self explanatory) the game engine that Rockstar created and that runs GTA.
2. It is no one in the community's fault that Rockstar are completely anti-modding and have constantly tried to shutdown mod creators and mod access at every opportunity they can. 
3. In that regard it makes sense why GTA V is worse than GTA IV - Rockstar have gotten more advanced and more anti-mod.
4. Everything we have in terms of modding Rockstar games is because amazing talented people have found smart workarounds to all the roadblocks Rockstar have put in place. 
 
This community is filled with amazing people who have dedicated so much time and effort for free to help ungrateful people like you time and time again.
Do you know why any of those troubleshooting steps are known? Because people like A Stranger (Head of the RPH discord and creator of the RPH faq(which has every known possible solution to the SlimDX error for example)), and many others, have spent years of their lives, thousands of hours of their free time, dedicated to helping people and finding solutions to the problems that come along with modding a game that does not want to be modded. 
 
I'm sure it's frustrating to try and solve such an annoying issue when you just wanna play the game. But don't take it out on the people who are the ones that are literally trying to help and have laid the groundwork for every troubleshooting step you have tried so far for this issue and every other known issue. 
 
In conclusion double check the RPH FAQ double check every step as everything known about that error is documented there.
 
P.s. when dealing with problems it's always good to be specific - For GTA V it's called LSDPFR not LCPDFR

If you installed mod files in the mods folder, like has been recommended for years now, this is literally impossible.
1. (I know it was tongue in cheek but) Rage stands for Rockstar.Advanced.Game.Engine ("plugin hook" is pretty self explanatory) the game engine that Rockstar created and that runs GTA.
2. It is no one in the community's fault that Rockstar are completely anti-modding and have constantly tried to shutdown mod creators and mod access at every opportunity they can. 
3. In that regard it makes sense why GTA V is worse than GTA IV - Rockstar have gotten more advanced and more anti-mod.
4. Everything we have in terms of modding Rockstar games is because amazing talented people have found smart workarounds to all the roadblocks Rockstar have put in place. 
 
This community is filled with amazing people who have dedicated so much time and effort for free to help ungrateful people like you time and time again.
Do you know why any of those troubleshooting steps are known? Because people like A Stranger (Head of the RPH discord and creator of the RPH faq(which has every known possible solution to the SlimDX error for example)), and many others, have spent years of their lives, thousands of hours of their free time, dedicated to helping people and finding solutions to the problems that come along with modding a game that does not want to be modded. 
 
I'm sure it's frustrating to try and solve such an annoying issue when you just wanna play the game. But don't take it out on the people who are the ones that are literally trying to help and have laid the groundwork for every troubleshooting step you have tried so far for this issue and every other known issue. 
 
In conclusion double check the RPH FAQ double check every step as everything known about that error is documented there.
 
P.s. when dealing with problems it's always good to be specific - For GTA V it's called LSDPFR not LCPDFR

In regards to why decals are broken, decals depend on an ambient connection to GTA Online.
RAGEPluginHook aggressively blocks any communication to GTA Online (more so than Scripthook V for instance) to prevent you from being banned.

This is simply not true. 
SHV and ELS are 100% stable. The only time they may cause crashes is through user error or windows interfering with them. 
Furthermore if you had an issue with ELS... That would reflect on ELS not on SHV.

And added the exception? Re-installing does nothing if you didn't perform the primary function for re-installing.
 
Sounds like an issue with an ELS xml and not ScriptHookV. Again, mine works perfectly fine. Never had an issue to this day.
 
I consulted with someone on this and they stated that for most cases involved "System.IO.IOException" in the crash message, first thing worth trying is anti-virus exceptions.

But I digress, simply try my solution and give us the results of the test.