Skyrim Anniversary Edition might break your Special Edition mod list, here's why

As a way to celebrate the decennial anniversary of Skyrim's 11.11.11 release, Bethesda released Skyrim's 'Anniversary Edition' last november.

As a free upgrade to everyone who owns a digital copy of Skyrim Special Edition, this new release comes with all the Creation Club content released thus far - including all-new gear, large-scale quests, and gameplay mechanics like fishing.

This also makes Skyrim the only Bethesda game to get four separate releases (the original release, Legendary Edition, Special Edition, and Anniversary Edition). For a single-player game to last beyond a decade and hold enough relevance for major content add-ons like this, is a rare feat to say the least. For Skyrim in particular, its ever-renewing popularity comes largely from its expansive mod community.

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Older Skyrim mods that do not work on Anniversary Edition

Currently, there are nearly 44,000 mods with over a billion cumulative downloads for the Skyrim Special Edition Nexusmods page; a number which is even higher for the old Skyrim Legendary Edition, otherwise known as oldrim.

Such a huge number of mods warrant modlists of all shapes and sizes. As a matter of fact, the Skyrim modding resources rabbit hole goes deep enough that there are numerous community tools dedicated towards sorting someone's modlist to ensure the best degree of compatibility.

With the release of Anniversary Edition, however, the otherwise stable stupor of compatibility has been disrupted. Anniversary Edition's content add-ons are largely new game files with esp (Elder Scroll Plugins) files that can be disabled and enabled individually. A vast majority of mods will therefore not break the game outright, despite some compatibility and balance issues for overhaul mods like Y.A.S.H, which have not yet been updated to address the new free content.

Hard-incompatibility cases, on the other hand, come from Skyrim Script Extender or SKSE64 mods.

In short, Skyrim Script Extender is a commonly used tool for the PC release that extends the scripting functionalities of the game engine. A number of mods draw on this as a base requirement. The SKSE tool needs to be compatible with the exact Skyrim binary, which changes with each game update.

While SKSE64 itself has been updated by its hard-working team to match the Anniversary Edition release, many SKSE mods meant for Skyrim Special Edition (1.5.97 or older Skyrim binaries) will not function properly until they are updated. This unfortunately also includes some oft-used modding essentials such as Skyrim Engine Fixes, whose beta release for Skyrim Anniversary Edition (1.6.342) is non-functional at the moment.