My friend recently tamed an overworld Drake, and while travelling the server crashed. After restarting the server and my friend logging in The server crashed again. Only fix was removing his Player data as the Drake would only appear when he joined the server because he was still riding it, and we couldn't get rid of just The drake because it wouldnt even render.

for more details the server in running on forge and bukkit. I also attached the mod list and server log during crash

I need the full log containing the stack trace of the crash. Yes the erroring entity is useful but not enough to know what actually is going on here.

I've been experiencing a similar issue, whenever me and my friends get close to an overworld drake, the whole server closes and says there's an error with entity overflow, and it's Only the overworld drakes doing it, we can get close and even tame any other wyrmroost dragon so we've just settled with using the /kill command to specifically kill overworld drakes

As I've stated before, I don't have enough information. If you can provide the proper CRASH LOGS I'll be able to help and know how to fix the problem. So far I have nothing.

What version of the mod are you using?
I was sure I've fixed this before...

Got the crash logs
(Dunno how to exactly post everything except the freaking link btw, so bare with me)
https://mclo.gs/GJEmUqf