[Python] Discord voice WebSocket 4006 "Session is no longer valid" error with Nextcord...

I’m developing a Discord bot in Python using Nextcord, with classic prefix commands. I want the bot to join a voice channel when a user sends a command.

However, when running the voice join command, the connection repeatedly fails with the following error in the logs:

nextcord.errors.ConnectionClosed: Shard ID None WebSocket closed with 4006


This error happens multiple times during reconnect attempts.

Environment and tests

• I get this error both on Linux and Mac.
• I tested the bot using my 4G connection to exclude potential issues with my home network/firewall.
• Despite that, the error still occurs.
• I suspect that something related to the voice connection is not properly cleaned up or closed, which leads to the session becoming invalid and the connection failing.
• Previously, the code was working correctly.
• Sometimes it still works, for example if I haven't restarted the bot for a long time, but this is very rare.

What I did (full code)


import logging
import nextcord
from nextcord.ext import commands

logging.basicConfig(
format="%(asctime)s [%(levelname)s] %(message)s (%(filename)s:%(lineno)d)",
level=logging.INFO
)

TOKEN=""

intents = nextcord.Intents.default()
intents.message_content = True
intents.voice_states = True

bot = commands.Bot(command_prefix="!", intents=intents)

@bot.command()
async def join(ctx):
channel = ctx.author.voice.channel if ctx.author.voice else None
if not channel:
await ctx.send("You must be in a voice channel.")
return

voice_client = nextcord.utils.get(bot.voice_clients, guild=ctx.guild)

if voice_client and voice_client.is_connected():
await voice_client.move_to(channel)
else:
try:
await channel.connect()
except nextcord.errors.ConnectionClosed as e:
print(f"Voice connection error: {e.code} - {e.reason}")

bot.run(TOKEN)

Logs when running


2025-08-13 01:28:44,038 [INFO] logging in using static token (client.py:685)
2025-08-13 01:28:44,043 [INFO] Allowed 1 rate limits to be garbage collected. (http.py:712)
2025-08-13 01:28:44,495 [INFO] Shard ID None has sent the IDENTIFY payload. (gateway.py:435)
2025-08-13 01:28:44,685 [INFO] Shard ID None has connected to Gateway: [...] (gateway.py:526)
2025-08-13 01:28:58,632 [INFO] Connecting to voice... (voice_client.py:346)
2025-08-13 01:28:58,633 [INFO] Starting voice handshake... (connection attempt 1) (voice_client.py:328)
2025-08-13 01:28:58,932 [INFO] Voice handshake complete. Endpoint found c-cdg15-a5a2903c.discord.media (voice_client.py:332)
2025-08-13 01:28:59,044 [ERROR] Failed to connect to voice... Retrying... (voice_client.py:374)
Traceback (most recent call last):
...
nextcord.errors.ConnectionClosed: Shard ID None WebSocket closed with 4006
2025-08-13 01:29:00,051 [INFO] The voice handshake is being terminated for Channel ID ... (voice_client.py:321)
... (repeated attempts with the same 4006 error)


Thanks a lot for your help!

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