Never open Skyrim through Steam or the default Bethesda launcher. Always launch the game using skse64_loader.exe via your Mod Manager (MO2 or Vortex). Because Steam is already open in the background, launching through SKSE tricks Steam into thinking the game is running without triggering the pending update download.
As confirmed by a Skyrim Starter Pack collection on Nexus Mods: "I used build 2.2.3 (game version 1.6.640), even though I only have Skyrim SE".
When a mod author or guide says "Verified for 1.6.640" , it means:
If you are looking at modding guides, Nexus Mods, or community forums, you will often see references to (sometimes written as build 16640). Here is what you need to know. skyrim special edition 16640 verified
For mod lists like Legacy of the Dragonborn or Wildlander , 16640 is the recommended runtime.
Game crashes immediately after the Bethesda logo when launching through SKSE.
To keep your build stable on this version, ensure you use these specific versions of core tools: Never open Skyrim through Steam or the default
Some mods have proven more problematic on 1.6.640:
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. Why special edition SkyrimSE.exe says version 1.6.640.0
Released in late 2022, version was a major update that primarily targeted the PC (Steam) version of the game. It followed the initial, somewhat chaotic release of the Anniversary Edition (1.6.x) and aimed to fix several stability issues and bugs introduced by the creation of that new edition. As confirmed by a Skyrim Starter Pack collection
The power of 1.6.640 lies in the "Address Library for SKSE Plugins." This library acts as a translator. While 1.6.640 is technically an "AE" version, it is the final version that major library authors verified before Bethesda changed the compiler flags. Newer versions (1.6.1130+) introduced code that confused the Address Library, leading to crashes on startup.
If you are looking to run a heavily modded game without dealing with the constant breakage of newer AE updates (like 1.6.1130 and beyond), this guide will walk you through verifying your game, downgrading if necessary, and setting up a stable environment. Why 1.6.640 is the "Verified" Version