我的机器人使用 Discord.py 自动对新消息做出反应，并在 25 颗星后将其添加到 starboard。但是经过一段时间的运行后，会出现此错误： 忽略 on_raw_reaction_add 中的异常

Ignoring exception in on_raw_reaction_add
Traceback (most recent call last):
  File "C:\Users\timpi\AppData\Local\Programs\Python\Python38-32\lib\site-packages\discord\client.py", line 312, in _run_event
    await coro(*args, **kwargs)
  File ".\main.py", line 36, in on_raw_reaction_add
    message = await reactchannel.fetch_message(payload.message_id)
  File "C:\Users\timpi\AppData\Local\Programs\Python\Python38-32\lib\site-packages\discord\abc.py", line 935, in fetch_message
    data = await self._state.http.get_message(channel.id, id)
  File "C:\Users\timpi\AppData\Local\Programs\Python\Python38-32\lib\site-packages\discord\http.py", line 223, in request
    raise NotFound(r, data)
discord.errors.NotFound: 404 Not Found (error code: 10008): Unknown Message

这是 on_raw_reaction_add 事件：

@bot.event
async def on_raw_reaction_add(payload):
    channel_id = int(config["channelIDMemephone"])
    reactchannel = bot.get_channel(channel_id)
    message = await reactchannel.fetch_message(payload.message_id)
    await star_post_check(message)

这是完整代码：

import discord, json
from discord.ext import commands

# Loading the config from a JSON file
config = json.load(open('config.json'))

# Linking variables to the config.json
react_channel = int(config["channelIDMemephone"])
starboard_channel_id = int(config["channelIDStarboard"])
star_emoji = config["powerstar"]
required_stars = int(config["starboardlimit"])
token = config["token"]

# Bot "metadata"
bot = commands.Bot(command_prefix='$', description="A star bot.")


# Execute this as the bot logs in
@bot.event
async def on_ready():
    print('Logged in as {}'.format(bot.user.name))
    await bot.change_presence(activity=discord.Game(name='with stars'))

# Add a star to every new message in the specified channel
@bot.event
async def on_message(message):
    if int(message.channel.id) == react_channel:
        await message.add_reaction(star_emoji)

#Call the star_post_check() function on every added reaction
@bot.event
async def on_raw_reaction_add(payload):
    channel_id = int(config["channelIDMemephone"])
    reactchannel = bot.get_channel(channel_id)
    message = await reactchannel.fetch_message(payload.message_id)
    await star_post_check(message)

#Checking if the post has more than 25 Stars and if so sending an embed to the starboard channel
async def star_post_check(message: discord.Message):
    if str(message.id) in open('sent.txt').read():
        match = True
    else:
        match = False
    if match:
        return
    add_to_starboard = False
    starboard_channel = discord.utils.get(message.guild.channels, id=starboard_channel_id)
    for i in message.reactions:
        if i.emoji == star_emoji and i.count >= required_stars and message.channel != starboard_channel:
            add_to_starboard = True
    if add_to_starboard:
        # embed message itself
        starboard_embed = discord.Embed(title='Starred post', description=message.content, colour=0xFFD700)
        starboard_embed.set_author(name=message.author, icon_url=message.author.avatar_url)
        try:
            if message.content.startswith('https://'):
                starboard_embed.set_image(url=message.content)
        except:
            pass
        try:
            starboard_embed.set_image(url = message.attachments[0].url)
        except:
            pass
        # sending the actual embed
        await starboard_channel.send(embed=starboard_embed)
        cache = open("sent.txt", "a")
        cache.write(str(message.id) + " ")
        cache.close()

bot.run(token)