If you're not recieving any errors in your console, even though you know you should be, try this:

With bot subclass:¶

import discord
from discord.ext import commands

import traceback
import sys

class MyBot(commands.Bot):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

    async def on_command_error(self, ctx: commands.Context, error):
        # Handle your errors here
        if isinstance(error, commands.MemberNotFound):
            await ctx.send("I could not find member '{error.argument}'. Please try again")

        elif isinstance(error, commands.MissingRequiredArgument):
            await ctx.send(f"'{error.param.name}' is a required argument.")
        else:
            # All unhandled errors will print their original traceback
            print(f'Ignoring exception in command {ctx.command}:', file=sys.stderr)
            traceback.print_exception(type(error), error, error.__traceback__, file=sys.stderr)

bot = MyBot(command_prefix="!", intents=discord.Intents.default())

bot.run("token")

Without bot subclass¶

import discord
from discord.ext import commands

import traceback
import sys

async def on_command_error(self, ctx: commands.Context, error):
    # Handle your errors here
    if isinstance(error, commands.MemberNotFound):
        await ctx.send("I could not find member '{error.argument}'. Please try again")

    elif isinstance(error, commands.MissingRequiredArgument):
        await ctx.send(f"'{error.param.name}' is a required argument.")
    else:
        # All unhandled errors will print their original traceback
        print(f'Ignoring exception in command {ctx.command}:', file=sys.stderr)
        traceback.print_exception(type(error), error, error.__traceback__, file=sys.stderr)

bot = commands.Bot(command_prefix="!", intents=discord.Intents.default())
bot.on_command_error = on_command_error

bot.run("token")

Make sure to import traceback and sys!

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Useful Links: - FAQ - Simple Error Handling