Luckily, there’s a work-around
The fourth Assassin’s Creed Unitypatch released yesterday, and Xbox One users found that it was substantially larger than advertised. The update, which was meant to be 6.7GB, clocks in at 40GB on the Microsoft console. The only thing getting assassinated around here anytime soon is your hard drive.
Ubisoft addressed the issue on the Assassin’s Creedsite, stating that the update is unintentionally replacing the entire game rather than just the areas that the patch targets for users that have previously applied the third patch. The publisher’s working with Microsoft to reduce the download to the intended size, but has no estimated time-frame for a solution.
However, Ubisoft has a work-around. Uninstalling and then re-installing Unityis said to revert the patch to its correct form. That should be relatively quicker for those with physical copies than downloading 40GB. Sorry, anyone with bandwidth caps!
Patch 4 Release Notes [Updated] [Assassin’s Creed]