[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"problem-detail-warning-python-app-answers-because-its-code-uses-an":3},{"stack":4,"error":5,"seoName":6,"seoStack":7,"seo":8,"breadcrumb":10,"titlePrefix":17,"titleAccent":18,"lead":19,"facts":27,"why":42,"log":47,"fix":51,"engine":60,"related":64,"pitch":72},"python","python-app-answers-because-its-code-uses-an","Python app answers 500 because its code uses an API removed from an unpinned dependency","Python",{"description":9},"The application started but did not answer on any port it publishes. The deploy log has the per-port result; a worker or queue-only app can ignore this. | The s",[11,14,16],{"label":12,"href":13},"App Installations","\u002Fapps",{"label":7,"href":15},"\u002Fapps\u002Fstacks\u002Fpython",{"label":6},"Python app answers 500 because ","its code uses an API removed from an unpinned dependency",[20,22,25],{"text":21},"The application started but did not answer on any port it publishes. The deploy log has the per-port result; a worker or queue-only app can ignore this. | The site returned 500 instead of a page. The 500 came back in about 2ms -- too fast for the application to have answered. A proxy returned it -- the engine's, or one the image runs in front of the app -- because nothing answered behind it: the container never started or is crash-looping. Read the container's STARTUP output with ",{"text":23,"code":24},"docker logs",true,{"text":26}," -…",[28,33,36,38],{"label":29,"value":30,"tone":31,"tooltip":32},"Type","Warning","warn","An issue PanelAlpha Engine catches around a deploy that does not break it. It tells you, before or after, that you may need to do something.",{"label":34,"value":35},"Seen","3 times",{"label":37,"value":7},"Where",{"label":39,"value":40,"tooltip":41},"Status","In Analysis","Our team will look into this soon, verify the cause and try to fix it in an upcoming release.",{"heading":43,"body":44},"Why it happens",[45],{"text":46},"The application starts, but the front page raises an error inside the app: the current FastAPI\u002FStarlette release no longer accepts the old TemplateResponse call the code makes.",{"heading":48,"block":49},"",{"header":48,"lines":50},[],{"heading":52,"steps":53,"block":57},"How to fix it",[54],[55],{"text":56},"Pin the framework versions the code was written for in requirements.txt (for example starlette\u003C1), or update the call to TemplateResponse(request, \"index.html\"), then redeploy.",{"header":58,"lines":59},"Fix by hand",[],{"heading":48,"body":61,"block":62},[],{"header":48,"lines":63},[],{"heading":65,"items":66},"Apps affected",[67],{"title":68,"badge":69,"tone":70,"href":71},"Msdocs Python Fastapi Webapp Quickstart","3 occurrences","err","\u002Fapps\u002Fazure-samples\u002Fmsdocs-python-fastapi-webapp-quickstart",{"heading":73,"body":74,"footNote":75,"docsLabel":76,"docsHref":77},"Try PanelAlpha Engine yourself.","The easiest way to turn your server into a safe, controlled environment for your AI agent. Deploy, manage and maintain any project from Claude Code, Cursor, Codex or any other MCP client. Open source under Apache 2.0, free to run.","Requires Ubuntu 24.04 or 26.04 · 2 GB RAM · 1 CPU","Read the documentation","https:\u002F\u002Fpanelalpha.com\u002Fdocs"]