You must accept the EULA
Minecraft refuses to run until you accept Mojang's EULA. Set eula=true in eula.txt via the Files tab, then restart.
On its first start a Minecraft server writes a file called eula.txt and then stops, printing a message that you must agree to the Mojang End User Licence Agreement (available at https://aka.ms/MinecraftEULA). This is normal and happens once per server. You just need to change one line and start again.
Accept it from the Files tab (easiest)
- 1Open the Files tab and find
eula.txtin the server root. - 2Open it for editing — you will see
eula=false. - 3Change it to
eula=trueand save. - 4Go back to the Console tab and press Start.
No eula.txt yet?
The file only appears after the server has tried to start at least once. If you do not see it, press Start, let it stop, then refresh the Files tab.
One and done
You only accept the EULA once per server. It stays accepted through restarts and updates. You would only need to redo it after a full reinstall that wipes files.