Plugin api version is 2 while 3 is required

no, you don’t.

Follow these steps:
1. Stop your old server instance (Do not kill it! Or else you will not be able to start your new server for the next 2-3 hours!)
These are official supported ways. to shutdown the whole server.
All ways will shutdown the whole instance and will report, that slots are not used anymore.

All operation systems:
The ServerQuery command serverprocessstop.
click me to get an "how to use the Query Interface with Putty"

Windows:
Right-click into the Server Tray Icon -> Then press Exit

Linux/FreeBSD shell:
The command ./ts3server_startscript.sh stop if your server was started with ./ts3server_startscript.sh start

2. Make a copy of the existing ts3server.sqlitedb to have a backup in case something bad happens.
*Make a backup of your TS database in MariaDB/MySQL in case you do not use SQLite

3. Download the right server package from TeamSpeak Downloads | TeamSpeak

4. Extract the server package

5. Overwrite the server files and folders with the extracted content. Then paste the ts3server.sqlitedb file

6. On Windows/Mac OS start the ts3server binary.
On Linux/FreeBSD start the server with the ts3server_startscript.sh
(First start can take some time)

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