Steps to Reproduce:
1) Open server.properties
2) Set max-players to -1 and save
3) Start the server
Expected:
The server doesn't start
Observed:
The server saves its player limit as -1
MC-265231
A server's player limit can be set to 0 or less
Open
1
I'd say resetting back to 20 would be odd, logging an error and closing the server would make more sense. (Just like when EULA flag isn't set to true.)