Mods that add extra joints to the default character.ragdoll, such as the "improved reforger ragdolls" mod from the workshop, will crash or cause extreme lag to a multiplayer server if a non-host player becomes a ragdoll by dying or becoming incapacitated.

When the server host is ragdolled no issues occur, so the crash never happens in singleplayer. In a multiplayer game however, a non-host player ragdoll will always crash the server or cause extreme lag. As such, server owners cannot run ragdoll mods without experiencing frequent crashes.

If character.ragdoll is modified but does not add any extra joints from default, the crash does not occur.

Logs are included in 'additional information'.
Interesting log lines:
14:56:04.398 PHYSICS (W): Overflow in AABB, object removed from simulation
14:56:07.723 DEFAULT (E): ParticleEffectComponent: Suspicious parent velocity (inf km/h) for particle effect 'Particles/Enviroment/Bleeding_01_Continuous.ptc'.