此问题的常见原因是与Youtube dl库的版本问题有关。尝试升级或降级此库版本，以便与Discord py库兼容。以下是一个示例代码片段，显示如何在Discord.py中使用最新版本的Youtube dl：

import discord
from discord.ext import commands
import youtube_dl

# set youtube_dl options
ytdl_options = {
    'format': 'bestaudio/best',
    'outtmpl': '%(extractor)s-%(id)s-%(title)s.%(ext)s',
    'restrictfilenames': True,
    'noplaylist': False,
    'nocheckcertificate': True,
    'ignoreerrors': False,
    'logtostderr': False,
    'quiet': True,
    'no_warnings': True,
    'default_search': 'auto',
    'source_address': '0.0.0.0' # ipv6 addresses cause issues sometimes
}

class Music(commands.Cog):
    def __init__(self, client):
        self.client = client

        self.voice = None
        self.queue = []

    async def join_voice_channel(self, ctx):
        if ctx.author.voice:
            self.voice = await ctx.author.voice.channel.connect()
        else:
            await ctx.send("You need to be in a voice channel to use this command.")

    @commands.command()
    async def play(self, ctx, *, url):
        await self.join_voice_channel(ctx)

        player = await YTDLSource.from_url(url, loop=self.client.loop, stream=True, ytdl_options=ytdl_options)
        self.queue.append(player)

        if not self.voice.is_playing():
            await self.play_next()

    async def play_next(self):
        if len(self.queue) > 0:
            player = self.queue.pop(0)
            self.voice.play(player, after=lambda e: print(f'Player error: {e}') if e else None)
        else:
            await self.voice.disconnect()

client = commands.Bot(command_prefix='!', case_insensitive=True)
client.add_cog(Music(client))
client.run('token')

此代码片段使用了discord.py和youtube_dl库，以创建一个可以播放从YouTube链接获取