Minecraft just got an unhadle error and I can't join the server back [1.16]

So i was trying to use a command that give you netherite chestplate with enchantments protection 10000 and unbreaking 10000 and when I enter the command, I suddenly leave from my server with error:

```

[12:05:05] Netty Epoll Server IO #0/ERROR: java.lang.IllegalArgumentException: Invalid key. Must be [a-z0-9/._-]: 

[12:05:05] Netty Epoll Server IO #0/ERROR: java.lang.IllegalArgumentException: Invalid key. Must be [a-z0-9/._-]: 

```

 I try rejoin but I keep disconnecting. I think the cotmmand did work but the item I get is bugging