I dont know what this error is or what is causing it. Im not being spammed by it and have done multiple searches. 
Does anyboby have any idea whats causing it?
Item.SetParent caused remove - this shouldn't ever happen

I have the same spam in the console periodically
Item.SetParent caused remove - this shouldn't ever happen

I'm having the same issue, I'm using a custom made map that I've been working on and thought it could be that but I am unsure.

The problem is not the map. I have already had several wipes on different maps. The error does not disappear.

this happened to me too when the skinner plugin is used. 

Item.SetParent caused remove - this shouldn't ever happen

yukionna

this happened to me too when the skinner plugin is used. 

Item.SetParent caused remove - this shouldn't ever happen

@yukionna - did you ever narrow down what caused it 100%? I'm using Skinner on 3 servers I manage and this only appears to happen on one of them randomly. I'm not entirely sure it's related to Skinner to be honest. My players seem to get disconnected as well.

In checking my server.log file I do see the following line items that I suppose would cause concern:

Rcon Error: System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
. ---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host.

  at System.Net.Sockets.Socket.EndReceive (System.IAsyncResult asyncResult) [0x00012] in <14e3453b740b4bd690e8d4e5a013a715>:0 
  at System.Net.Sockets.NetworkStream.EndRead (System.IAsyncResult asyncResult) [0x00057] in <14e3453b740b4bd690e8d4e5a013a715>:0 
   --- End of inner exception stack trace ---
  at System.Net.Sockets.NetworkStream.EndRead (System.IAsyncResult asyncResult) [0x0009b] in <14e3453b740b4bd690e8d4e5a013a715>:0 
  at Fleck.WebSocketConnection+<>c.<Receive>b__63_0 (System.IAsyncResult result) [0x00017] in <ab99eefdd17e4a4e88de8ba5c29af877>:0  
(Filename: C:\buildslave\unity\build\Runtime/Export/Debug/Debug.bindings.h Line: 35)

In addition to seeing the following:

Item.SetParent caused remove - this shouldn't ever happen 
(Filename: C:\buildslave\unity\build\Runtime/Export/Debug/Debug.bindings.h Line: 35)

Im getting the same
Item.SetParent caused remove - this shouldn't ever happen