Troubleshooting aiohttp ServerDisconnectedError

If you're using Python's aiohttp library for asynchronous HTTP requests and getting ServerDisconnectedErrors, it usually means the server closed the connection unexpectedly. This can happen for a variety of reasons - let's walk through some troubleshooting tips.

First, check the server logs if possible to see if there are errors or connectivity issues on their end. Many times the problem isn't with your client code but rather something happening on the server.

If the server looks healthy, next take a closer look at where in your aiohttp code the exception is happening. The most common culprits are:

async with aiohttp.ClientSession() as session:
    async with session.get(url) as response:
        response.text() # ServerDisconnectedError happens here

Or:

async with aiohttp.request('GET', url) as response:
   response.text() # Bingo - disconnected here

The issue is that you're trying to get the response content after the connection closes. Instead, move your response handling logic inside the request context manager:

async with aiohttp.request('GET', url) as response:
    text = await response.text() # Won't disconnect
    # process text here

This waits for the response content inside the context manager, before the connection can close.

Another cause can be exceeding a connection pool limit. Try lowering connector = aiohttp.TCPConnector(limit=10) or retry the request.

Also check for proxies, VPNs, or firewalls that may be interfering with long running connections.

Finally, the server itself could be terminating idle connections too aggressively. If possible tweak settings on that end.

I hope these tips help troubleshoot your aiohttp disconnected errors! The key is to handle the response inside the context manager to prevent premature closing, check connectivity issues, and ensure your client isn't overloading connections.