chat input error ... plz help

I'm a GM who runs CoC sessions and my PC just typed text and pressed Send, but his chats get an error. The error message is 'There was an error with your formula. Please try again'. I didn't use any macros and it's not like there's a character journal with the same name. It's driving me crazy because it's like this three times and once. Do you know why this is happening and how to fix it?

What was the player typing? That may help to see what is going wrong. 

Hi 김정분! if you are unable to resolve this,  it could be a corrupted Chat Archive. A game's Creator is often able to fix issues with their Text Chat by  clearing the Chat Archive  (note: not  clearing your current Chat Log ). A GM might want to copy/back up the Chat Archive before the Creator clears it.

I found the cause. The PC says that the virtual keyboard automatically enters an invisible '/' in front of the chat to prevent hacking, but it seems to have been treated as a formula error. I'll refer to the above methods later on. Thanks for the help.