ChatGPT: Error in message stream
It’s not an issue with your device or internet connection. The problem is on their end. Usually, it’s a temporary backend or server connection issue, even if their status page is still green and says everything is fully operational.
https://status.openai.com/
You'll need to wait until the servers are restored
Try logging out, then log back in
Try using on another device, to check if the issue is device specific.