claude api stream not working

When developing with Claude, streaming responses via Server-Sent Events (SSE) allows you to display text in real time. However, network middleboxes, client buffering, or unhandled chunk fragmentation can cause the stream to hang or fail completely. Follow these steps to diagnose and repair your stream connection.

1. Disable response buffering in proxy servers

If your application sits behind a reverse proxy like Nginx, Apache, or Cloudflare, the proxy may attempt to buffer the entire response before sending it to the client. This breaks Server-Sent Events. To fix this on Nginx, add the header X-Accel-Buffering: no to your application's upstream response, or disable buffering in your server configuration block using proxy_buffering off;.

2. Customise your runtime buffer settings

Local runtimes can sometimes buffer console or network outputs. In Node.js or Python environments, verify that your stream reader does not wait for an EOF (End of File) marker. For instance, in Python, running your script with the unbuffered flag (python -u script.py) ensures that print statements and stream chunks are flushed to the terminal immediately instead of being held in system memory.

3. Handle chunk fragmentation in raw HTTP setups

If you are bypassing official SDKs and consuming the stream using a raw HTTP client, remember that individual TCP chunks do not always align with complete SSE events. Your parser must buffer incoming data fragments and split them by double newlines (\n\n) to isolate each data: block. Trying to parse an incomplete JSON fragment will throw immediate decoding errors.

4. Distinguish stream dropouts from complete outages

Sometimes a silent stream disconnect is actually a sign of a wider API outage rather than a code defect. If your code handles connection drops gracefully but the stream fails to establish any initial handshake, the entire service might be experiencing downtime; check our guide on Claude Not Responding to isolate network-wide outages.

5. Implement robust client-side reconnection logic

Always wrap your stream loop in a try-catch block that supports automatic retries with exponential backoff. When Claude terminates a connection prematurely due to transient network hiccups, your client code should read the last received message index and request a resumption or handle the error gracefully rather than letting the entire application crash.