I wanted to report a consistent issue affecting deployments via AI Studio when accessed from iOS and Safari browsers. After deploying my app (and others have too), streaming-based Gemini API calls fail.
Steps to reproduce
Deploy any Gemini streaming app using the AI Studio Deploy button.
Access it in Chrome desktop. It works perfectly.
Access the same URL on iOS Safari, Chrome, or Firefox. You get a 502 error saying “ReadableStream uploading is not supported”.
Errors are triggered when users attempt to use a feature requiring communication with Gemini. Example:
502 Bad Gateway - {“error”:“Proxying failed”,“details”:“ReadableStream uploading is not supported”}
Suspected cause
The client-side serviceworker.js injected by AI Studio wraps requests with duplex set to half, converting the request body into a streaming ReadableStream.
The default proxy container (us-docker.pkg.dev/cloudrun/container/aistudio/applet-proxy) does not support streaming uploads, which leads to the 502 error.
Multiple developers in community forums are encountering the same issue:
“Using Safari or Firefox … a proxy server doesn’t support ReadableStream for request bodies … leading to a 502 error.”
Impact
Breaks Gemini streaming use cases on all non-Chrome desktop browsers.
Affects users on iOS and Safari, which are widely used platforms.
Suggested fix
Please consider updating the default proxy container to support streaming uploads (ReadableStream or chunked transfer encoding). This would restore compatibility with iOS and Safari without requiring developers to manage custom proxies.
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