You need to agree to the EULA in order to run the server

What this actually means

Mojang requires an explicit EULA acceptance before a server will start.

How to fix it

Open eula.txt next to the server jar and set `eula=true`. That's the whole fix.

How to be sure it is this

Open eula.txt beside the server jar. It will say eula=false.

What it gets mistaken for

Some panels keep their own copy, so editing the file you found may not be the one the server reads. If it reverts, you edited the wrong one.

What to do next

Set eula=true and start again. Nothing else causes this.

What it looks like in your log

Search your crash report or latest.log for any of these:

You need to agree to the EULA
Go to eula.txt for more info

The free edition of Forge Server Doctor detects this one. It is a single Python file with no dependencies — point it at the report and it names the cause and the mod jar:

python3 forge_doctor.py crash-reports/crash-....txt