How to fix your game after this update, or any update for that matter. If you want the quick fix, 100% guaranteed, only takes 10 seconds, stop reading this post and check out Youtube for Saving Grace Bullshit.
Slow but steady wins the race.
Here is the TLDR in 9 steps. Assumes you have SH5 updated.
Update your gameconfig.xml. There are 751 versions in the most popular one, so select the right one (see below).
Backup your existing dlclist.xml and any customized files using OpenIV.
Copy the new update.rpf and update2.rpf from your GTA5 Update folder to your Mods Update folder. Backup your mod versions first.
Now restore the entries for your dlc addons in your dlclist.xml, carefully. Post here if unsure how to do this.
Disable all your mods by renaming dinput8.dll (in your game/root folder) to dinput8.bak and start your game. If your game doesn't load, or if it crashes, contact Rockstar Support because your problem has nothing to do with mods.
If your game runs properly in Vanilla, unmodded, then as the next step follow the steps in this guide. After following all the steps in that guide, without skipping any, move to the next steps:
If you found a problem with an asi mod in your game/root folder, disable it by moving it out or renaming it without the .asi extension, post your issue here or contact the author.
If you found a problem with your scripts folder, reinstall your scripts one by one until you find the issue or issues. Scripts can conflict with the update or be outdated because of changes in the update.
If you found a problem with your mods folder, reinstall your mods one by one until you find the issue or issues. Remember that peds and vehicles can conflict with each other, whether mods or R* game dlc.
Optional step: The steps above pertain to your mods only. However it's also possible that the new DLC is conflicting with existing addon mods. In this case you can simply remove the new dlc entries from dlclist.xml and see if that solves your problems. Remove the 2 lines below, permanently or temporarily. There are 2 new Christmas ones as well which can be disabled if all else fails. Some users claim it worked for them.
An excellent one is linked below. For new users: it is hidden under MISC rather than TOOLS and is described as gameconfig rather than gameconfig.xml, so you may have missed it.
As written above, the author prefers the more is more approach, so provides you with an excellent selection of 751 files, all neatly organized.
Start with one in the
Gta Config v30 for v 1.0.2802 folder.
For More Mods\Stock Traffic (Means Gta base) for the sake of stability. You can change it later.
John, You're Crazy!
Ok, if you have 100s or 1000s of addons and scripts, you may not want to reinstall one by one. In that case there are other methods. For example, remove half and test. If you have a problem you know you have an issue in that half, so take those and halve them again. Rinse and Repeat.
This method, while much faster, doesn't work for everything because the second half in your initial pass may also have issues. Or a mod from Half 1 could conflict with a mod from Half 2. Agreed? So a combination of methods might work best for you. If you're a new user, with just a few mods and scripts, definitely go one by one.
After the update, can someone on these forums fix your broken game with 100% certainty? Nobody here will be able to fix your game remotely for you. They can help you fix it, but only if you follow their advice to the letter, without skipping steps.
Some users are lucky and have their game up and running after a patch simply by updating SH5 and their gameconfig.xml. Why do their games work while yours, despite having updated the 2 files/mods above?
The answer is simple. Your setup is unique. You have different hardware, different versions of GTA5, and most importantly you have different mods, configured differently.
The simple steps I listed above will work for the majority of you. For the more challenging problems you will need to educate yourself to better understand how all the different modding puzzle parts work together to eventually find a specific solution to your specific problem.
Troubleshoot systematically, with laser focus. Shotgun approach is not recommended, particularly for new users.
Suggested Reading - Updates
Why does Rockstar break the game?
Recovering from a game update
Avoiding R* Update Headaches
Preparing for the Next Update
Suggested Reading - New Users
New Users - Important Mods Checklist
Quick Way to Play Without any Mods
Asking for Help
Suggested Reading - Troubleshooting
Ultimate Troubleshooting Guide
GTA5 911 Help and Checklist
Modding 101 - Knowledge Helps