Previously, unique items couldn’t be picked up when the inventory was full. Now, key/quest items and unique items will be picked up even if the inventory is full, exceeding the inventory limit as necessary. This applies to keys, spells, quest items, ammo types, gestures, etc.
This change should also resolve any potential issues with questlines where a required item couldn’t be picked up due to an "inventory full" message. Additionally, starting from patch 1.1.310, if the inventory is full, the items will drop to the ground so they can be picked up later.
Please note that the stash expansion is still in progress and will be available later this year.