Hello everyone,
I have the following issue:
I made this server with my computer to play only with a friend. Today we couldn't connect to the server.
I launched it as usual with a run.bat because I allocated 3 GB of RAM to it:
C:\Users\myname\Desktop\server_folder_name>java -Xmx3072M -Xms3072M -jar server.jar nogui
[14:58:47] [main/INFO]: Environment: authHost='https://authserver.mojang.com', accountsHost='https://api.mojang.com', sessionHost='https://sessionserver.mojang.com', servicesHost='https://api.minecraftservices.com', name='PROD'
[14:58:48] [main/WARN]: Ambiguity between arguments [teleport, destination] and [teleport, targets] with inputs: [Player, 0123, @e, dd12be42-52a9-4a91-a8a1-11c01849e498]
[14:58:48] [main/WARN]: Ambiguity between arguments [teleport, location] and [teleport, destination] with inputs: [0.1 -0.5 .9, 0 0 0]
[14:58:48] [main/WARN]: Ambiguity between arguments [teleport, location] and [teleport, targets] with inputs: [0.1 -0.5 .9, 0 0 0]
[14:58:48] [main/WARN]: Ambiguity between arguments [teleport, targets] and [teleport, destination] with inputs: [Player, 0123, dd12be42-52a9-4a91-a8a1-11c01849e498]
[14:58:48] [main/WARN]: Ambiguity between arguments [teleport, targets, location] and [teleport, targets, destination] with inputs: [0.1 -0.5 .9, 0 0 0]
[14:58:48] [main/INFO]: Reloading ResourceManager: Default
[14:58:48] [Worker-Main-8/INFO]: Loaded 7 recipes
[14:58:48] [Worker-Main-8/INFO]: Loaded 927 advancements
[14:58:50] [Server thread/INFO]: Starting minecraft server version 1.16.4
[14:58:50] [Server thread/INFO]: Loading properties
[14:58:50] [Server thread/INFO]: Default game type: SURVIVAL
[14:58:50] [Server thread/INFO]: Generating keypair
[14:58:50] [Server thread/INFO]: Starting Minecraft server on (it is the right IP, I double checked)
[14:58:50] [Server thread/INFO]: Using default channel type
[14:58:51] [Server thread/INFO]: Preparing level "world"
[14:58:51] [Server thread/INFO]: Preparing start region for dimension minecraft:overworld
[14:58:52] [Server thread/INFO]: Preparing spawn area: 0%
[14:58:52] [Server thread/INFO]: Preparing spawn area: 0%
[14:58:52] [Server thread/INFO]: Preparing spawn area: 0%
[14:58:53] [Server thread/INFO]: Preparing spawn area: 0%
[14:58:53] [Server thread/INFO]: Time elapsed: 2222 ms
[14:58:53] [Server thread/INFO]: Done (2.307s)! For help, type "help"
The 2 obvious problems I see are the warnings at the beginning and the spawn area not loading.
Do you know how I can solve this? Is it maybe a known issue?
Thank you everyone in advance!
Related issues
Comments

Thank you for answering so fast.
To my understanding the warnings are not a issue.
But for the part where the spawn area doesn't load, please take into consideration
first, that my PC is powerful enough (gtx1070 and i7 6th generation) and it has enough RAM (16) to run the server and
second, that the "Preparing spawn area" screen doesn't log the same progress information multiple times as in the linked issue.
It only happens 4 times before the server eventually "starts". So it doesn't happen as often as in the issue you linked.
See MC-139271 and MC-124672.
Both of these warnings are non-issues.