Error message minecraft server 1.12.2?

It has happened to me before:

The console says:

: java.lang.IllegalArgumentException: Name and ID can't both be blank

: java.lang.IllegalArgumentException: Name and ID can't both be blank

: java.lang.IllegalArgumentException: Name and ID can't both be blank

And kicks players

How can I fix it?

Hosted or rented yourself?

If rented, contact the provider for support.

If hosted yourself then give more information.
Which version? Spigot, vanilla?
Which Minecraft version? 1.15 or others
Where hosted Locally or a VPS on the Internet

Rented, 1.12.2 spigot

Then you should have a support you can ask?

They are responsible for it. You pay for that too.

OK thanks