This problem has NOT been tested on a Vanilla multiplayer server. So far this problem has occurred in worlds that are opened to LAN state or on a Realms server.

What I expected to happen was...:
all players should stay on the LAN/Realm server and should not be kicked by the command block mechanic

What actually happened was...:
Having more than 1 player in the game while running this mechanic for some reason disconnects all players apart from the host with an odd error message. I have screenshotted this below.
it will continue to kick other players apart from the host off until the mechanic is stopped.

Steps to Reproduce:
1. place the command blocks in the same position as in the screenshot
2. put the commands in their respective command blocks
3. open the world to LAN OR upload to a realms server and add a player
4. get at least one other player online with you so there are at least 2 players in the same world
5. place a Redstone block between the 2 repeating command blocks

the mechanic has a variable 'mapload' which is a dummy and is incremented by 1 every game tick by the repeat command block.
It displays a title command when 'mapload' is 1

this is just a small piece of a larger mechanic.