Community Cloud installs incompatible Streamlit/Starlette versions causing GZipResponder TypeError on startup

Using Streamlit
,
1

I’m unable to deploy any Streamlit application on Streamlit Community Cloud.

The issue is reproducible with a minimal application.

Repository contents:

app.py

import streamlit as st

st.title(“Hello”)

requirements.txt

streamlit

The application never starts. The error occurs before my code is executed.

Deployment log shows:

Using Python 3.14.6 environment

Installed packages include:

  • streamlit==1.61.0
  • starlette==1.4.0
  • uvicorn==0.52.1

The server then fails health checks with:

TypeError: GZipResponder.init() missing 1 required keyword-only argument: ‘thread_minimum_size’

Stack trace points to:

streamlit/web/server/starlette/starlette_gzip_middleware.py

The same error happens:

  • with a completely minimal app
  • with a requirements.txt containing only “streamlit”
  • after changing the configured Python version
  • with multiple different applications

Since the application code is never executed, this appears to be an incompatibility in the deployment environment rather than in the app itself.

Could you please investigate why Community Cloud is installing this package combination?

2

Hey, thanks for sharing such a clear, reproducible example and detailed logs—super helpful! :balloon: This issue is caused by an incompatibility between the latest Python version (3.14.x), Streamlit, and Starlette. Specifically, Streamlit Community Cloud is currently defaulting to Python 3.14.x, but the installed Starlette version (1.4.0) is not compatible with Python 3.14, leading to the TypeError: GZipResponder.__init__() missing 1 required keyword-only argument: 'thread_minimum_size' error before your app code runs.

This is a platform-level issue, not a problem with your app or requirements.txt. Community Cloud does not currently honor runtime.txt for Python version pinning, and you must select the Python version from the app’s settings in the Community Cloud UI. The error is reproducible with any minimal app and requirements, as confirmed by multiple users and forum reports. The Streamlit team is aware of this incompatibility and recommends using Python 3.10 or 3.11, which are officially supported and do not trigger this error. For now, set your app’s Python version to 3.10 or 3.11 in the Community Cloud “Advanced settings” and reboot the app. If you continue to see this error, it’s likely due to a recent platform update or a bug in dependency resolution, and you may need to wait for a fix from the Streamlit team or follow updates on the official forums and GitHub issues.

Sources:

3

Hey @sr.torrijos25,

Thanks for flagging. If you upgrade to the latest patch 1.61.1, the issue has been resolved. :raising_hands: