Server Exception: BaseRidableAnimal.ProcessQueue

I'm getting this error about 10 times PER SECOND. I am not sure what is causing it. :(

(23:06:44) | Server Exception: BaseRidableAnimal.ProcessQueue(23:06:44) | NullReferenceException: Object reference not set to an instance of an object(23:06:44) | Server Exception: BaseRidableAnimal.ProcessQueue
Restarted the server and that did not fix the issue.
Same here , it happens only sometimes, seems to be related to something done by players, but I dont know what is it.

(02:08:05) | Server Exception: BaseRidableAnimal.ProcessQueue

(02:08:05) | NullReferenceException

KerriganSon
Same here , it happens only sometimes, seems to be related to something done by players, but I dont know what is it.

(02:08:05) | Server Exception: BaseRidableAnimal.ProcessQueue

(02:08:05) | NullReferenceException

Do you have the Botspawn plugin?