Can't register tree command: Command 'foo' already registered.

[MeHaVr]

Why does it tell me 'foo' is already there? It was not registered anywhere else.

    @commands.Cog.listener()
    async def on_ready(self):
        await tree.sync(guild=discord.Object(id=1180536174633304184))
        print("ping.py says hello")

    @bot.tree.command()
    async def foo(self, interaction: discord.Interaction):
        await interaction.response.send_message('You must be the owner to use this command!')

Error:

discord.app_commands.errors.CommandAlreadyRegistered: Command 'foo' already registered.

[Rapptz]

Don't use @bot.tree.command() in a cog, use @app_commands.command() instead.

[Rapptz]

Your prefix shouldn't be /

[MeHaVr]

What prefixes are allowed? Ist it possible to use / for bot commands at all?

[itslychee]

it's not practical to use / for prefix commands when it's used for slash commands.

[MeHaVr]

How can I use slash commands?

[Link1O]

Firstly, refrain from syncing at the bot's startup; instead, utilize a prefix command for this action. Regarding the question 'How can I use slash commands?'—it's rather unclear what you're trying to convey.