For a comprehensive collection of fixes for Dawnguard called the Unofficial Patch Dawnguard (UDGP) Dawnguard, error correction is not fixed by the developers.
Requirements: ATTENTION! Unofficial patch will only work on versions of Skyrim not lower than 1.9.32.0.8! An Unofficial Patch Skyrim
When the Unofficial Patch, Skyrim Unofficial Patch and Unofficial Hearthfire Dragonborn Patch the boot order should be as follows:
Skyrim.esm Update.esm Unofficial Skyrim Patch.esp dawnguard.esm Unofficial Dawnguard Patch.esp HearthFires.esm Unofficial Hearthfire Patch.esp Dragonborn.esm Unofficial Dragonborn Patch.esp [Other ESM] Official high resolution textures Unofficial patch to the textures high resolution [Other ESP]
The above steps will help you avoid conflicts with other modifications.
Possible problems: UDGP (and other mods) can sometimes lead to crashes of Skyrim at main menu (pressing ESC-quit the Game-> > Menu). This does not entail any additional problems, because in any case the player goes on the menu, that is, if you restart the game, it will be in this menu (which is undoubtedly better than the menu in the game, as a guarantee that the data from the old session is left). This may be caused by an attempt to clear the engine data and finding the data that they do not like. UDGP (and other mods) can cause temporary loss of static objects (walls, floors), if you are loading more than one fashion. This problem does not occur if you have only one mod. The bug can occur even in cells that are not affected by the modes. Apparently, this is a problem of the engine with layers. Normally, restart the game solves the problem. The exact explanations of the causes of the problem at the moment.