REI Failed to Reload ServerDisplayRegistryImpl (GameInstance.getServer() is null)

What the log looks like

java\.lang\.NullPointerException: Cannot invoke "net\.minecraft\.server\.MinecraftServer\.method_3772\(\)" because the return value of "dev\.architectury\.utils\.GameInstance\.getServer\(\)" is null
\[REI\] Failed to run end-reload task for reloadable \[ServerDisplayRegistryImpl\] in stage \[END\]
me\.shedaniel\.rei\.impl\.common\.registry\.displays\.ServerDisplayRegistryImpl\.getAllSortedRecipes

How to fix it

1. If REI's item panel and recipe lookups work normally in-game, you can safely ignore this log entry; it occurs on REI's background REI-ReloadPlugins thread and will not crash the client.
2. Update Roughly Enough Items (REI) and Architectury API to the latest Fabric releases matching your exact Minecraft 1.21.x version.
3. If recipes are missing or the tag tab shows 'Failed to resolve tags! No tag data' on a Fabric multiplayer server (Minecraft 1.21.2+), install matching versions of Roughly Enough Items and Architectury API on the server as well so recipe and tag data sync to clients.
4. If REI's item overlay and search bar are completely missing on Hypixel Skyblock, update or roll back your Skyblock REI integration mods—specifically Firmament (release 42.0.0 is known to break REI plugin loading; switching to a compatible Firmament build restores the item list).

Check your own log