Make sure any firewalls or security software you have installed aren't stopping LOOT from reaching the online masterlist.
-If LOOT still can't update its masterlist, it's likely due to connectivity issues that are beyond our control (e.g., a temporary outage or your ISP blocking the domain the masterlists are downloaded from). You can attempt to update it manually by downloading this file (or this ZIP if you can't access the previous site, just extract the prelude.yaml file from it), selecting "Open LOOT Data Folder" within LOOT's File menu and placing prelude.yaml in the prelude folder.
If LOOT still can't update its masterlist, it's likely due to connectivity issues that are beyond our control (e.g., a temporary outage or your ISP blocking the domain the masterlists are downloaded from). You can attempt to update it manually by downloading this file (or this ZIP if you can't access the previous site, just extract the prelude.yaml file from it), selecting "Open LOOT Data Folder" within LOOT's File menu and placing prelude.yaml in the prelude folder.
Then, using the following table, download the masterlist.yaml file for your game from the masterlist link (or extract it from the alternative ZIP) and place it in the corresponding game folder. Finally, disable the "Update masterlist before sorting" option in LOOT's settings until your connectivity issues have been resolved.
games\Morrowindgames\OpenMWgames\Obliviongames\Oblivion Remasteredgames\Skyrimgames\Skyrim Special Editiongames\Skyrim VRgames\Fallout3games\FalloutNVgames\Fallout4games\Fallout4VRgames\Nehrimgames\Enderalgames\Enderal Special Editiongames\Starfield