Failed to connect to server (Invalid session) on self-hosted Server

Hello,

I run a self-hosted server on a cloudhoster. Everthing worked fine, till today. I tried to connect to the server an got following error:

"Failed to connect to server (Invalid session)" see screenshot

The Serverversion and the Clientversion are both the tatest Minecraft Java-Edition 1.16.2

Yesterday it worked perfect.

I think it's an account issue, but I don't know…

I tried the following:

• Restarting the game
• Restarting the launcher
• Restarting the router
• Restarting the minecraft-server
• Restarting the remote machine
• Re"install" the server.jar with wget on the remote server
• Reinstall the Minecraft program on my mac

Nothing worked...

But I read that the online mode could help. If I set

online-mode=false

it could work... Because I don't need an real online server I tried this out. My friends and I connect direct to that IP.

Now I can connect, but my items, stats also are all gone ... they were saved on the online account I think... so I changed it back...

Now I running again in this issue

How can I fix this please?