I created a ticket reporting a bug in my game, because my savegame is no longer causing damage when I fall. An administrator asked me to perform a command, but the command doesn't work, I believe because when I created my world I selected to disable the commands.
The ticket I reported the bug:
https://bugs.mojang.com/browse/MC-169188
In the print:
"Comando desconhecido ou incompleto (portuguese)
In english: Unknown or incomplete command
Please, when you answer this ticket do not close it, wait for me to test and say if I could fix the problem or not.
Edit: Happy new year admin 🙂
The old ticket is not closed, you can still comment under it if you have further questions.
The bug mentioned by @unknown in your old issue is MC-160464. You can see how to resolve this bug in that issue.
Also, please keep in mind that Mojira is a bug tracker, not a Q&A community.