Before the release of the "Anniversary Edition" (AE) in late 2021, Skyrim Special Edition remained on version 1.5.97 for nearly two years. This period of stability allowed the modding community to build a massive library of complex mods, particularly those using the .
Skyrim version 1.5.97 is widely considered the most stable and compatible version for modding. This is because it predates the "Anniversary Edition" (v1.6+) update, which changed the compiler used for the game's code. Many essential plugins—particularly those relying on —were built specifically for 1.5.97 and may not have been updated or may function differently on newer versions. The USSEP Compatibility Issue skyrim ussep 1.5.97