UE5 Dedicated server Error: Assertion failed: Index != INDEX_NONE

Finally, there is the ONLY ONE solution this issue, don’t waste your time, all other suggestions are fake, except for the only correct solution proposed by [xuefujun].

So, change: Engine/Source/Runtime/Engine/Private/Animation/AttributeTypes.cpp
EDelayedRegisterRunPhase::ObjectSystemReady => EDelayedRegisterRunPhase::PreObjectSystemReady

& fully rebuild UE5 then.