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Graph/deployment-route-mismatch

Pattern

Deployment Route Mismatch

deployment-route-mismatch

A recurring production-only failure where FastAPI endpoints that work locally return 404 or appear missing on the frontend after deploying to Azure, leading teams to tweak startup/CORS/SSE settings instead of aligning the deployed app entrypoint and routing base paths.

Node Details

Public graph metadata

Updated5/1/2026

Connections

30 linked nodes

FastAPI route works locally on / but fails on Vercel

Building/starting a Next.js 14 App Router app with next-pwa fails on staging (Vercel) and production (AWS Amplify), with missing Next server files such as routes-manifest.json and required-server-files.json.

Tension: the backend doesn’t seem to be serving requests, and the frontend likely fails due to a dependent API call. Outcome: The deployment succeeds (`READY` state).

Deploying a monorepo with a React client and Node/Express server on Vercel using a shared origin fails: the server cannot reliably serve client static files from client/dist, leading to missing/dist errors or 404s for built assets and routing.

502 preflight error between Vue.js frontend and Express backend

When accessing a bad url supposed to be 404 have this error `This Serverless Function has crashed.` — Angular SSR deployed on Vercel Serveless Function. Tension: my angular app routing could never do the job of redirecting to the correct /404 or just display the 404 component.

Cannot find module '@azure/identity' — I deployed express app to Vercel. Tension: local and it works fine. Outcome: after deploy to vercel, I see this error.

after some time I get a `503 Service Unavailable` error — When I make a POST request to this endpoint, it starts processing. Tension: especially when using ngrok. Outcome: What is the best way to handle long-running POST requests in FastAPI?

TypeError in FastAPI when using APIRoute with a Router — trying to implement an `APIRoute` class to handle logic before and after the request (logging). Outcome: Removing `async` before the function definition solved it.

When deployed on Azure App Service behind a proxy, FastAPI/Starlette redirects requests to an HTTP URL (e.g., HTTP Location header in a 307) instead of preserving HTTPS. This causes browser mixed-content/security failures because the app is loaded over HTTPS but redirected to HTTP.

it says `404 not found` — I succesfully deployed my FastAPI app to azure, but when I try to access the routes. Tension: However, when I tested the same routes locally, they worked. Outcome: I've successfully deployed your code to Azure Web App and have been able to access the routes.

Protect FastAPI routes so that authenticated users without the required permissions/roles cannot access specific endpoints.

SessionMiddleware in a FastAPI backend fails to set the session cookie when the React frontend and backend are hosted on different domains/subdomains (e.g., XXX-ui.fly.dev vs XXX-api.fly.dev). The browser rejects the cookie with an 'invalid domain' error and no session is maintained.

When deployed behind a Kubernetes/API-gateway URL prefix (e.g., https://api-gateway.example.com/myapp), FastAPI tried to load OpenAPI from a path missing the prefix (e.g., /api/v1/openapi.json), causing a 404 and failing to load API definitions.

After moving SQL endpoints from `main.py` into an `APIRouter` in `analytics.py`, database dependencies that worked in `main.py` no longer function correctly and errors occur (e.g., import/circular dependency issues).

I want to expose endpoints as follows: `/{master_i}/{db_j}/{tables_xyz}` — FastAPI Routing Question. Tension: the logic shouldn't change between the `.../db1/table1` part.

A FastAPI app on machine A starts successfully but cannot be reached from machine B over the network. Connections fail despite the server running without errors.

The Flutter Linux app calling local FastAPI endpoints fails with a DioException [bad response] due to an HTTP 307 (Temporary Redirect). Postman requests succeed, but the app always receives the redirect response.

Defining FastAPI routes in a loop causes each endpoint to behave like the last model

Deployment fails silently when code includes azure-identity

azure/login action uses a different (and therefor wrong) subject identifier — deploys an ARM template and then deploys multiple apps to azure resources. Tension: results in the deployment of the apps failing.

Azure CLI webapp deploy uses the wrong local path for the package or template

New Azure project lacks a clear Bicep folder/template structure for multiple environments and resources

A React frontend POST to http://localhost:4000/api/checkout consistently returns 404 Not Found even though an Express route for checkout is defined.

React SPA routes fail when copied and pasted URLs are not working

ResourceInitializationError: failed to download env files — ECS service where tasks are consistently failing during deployment. Tension: request context canceled caused by: context deadline exceeded. Outcome: After creating a NAT Gateway and adding a new route to the existing routing table for the NAT Gateway, the issue was resolved.

Not Found: /.env — running live in production on Azure VM. Tension: These look like someone is trying to scan my VM/app in order to find `.env` file, login credentials, etc.

delete fails with 404, meaning it can't find the endpoint — My react app successfully gets and posts from/to Spring Boot JPA MySQL db. Tension: delete fails with 404. Outcome: meaning it can't find the endpoint.

we are seeing 500 errors when hitting some backend endpoints — we have a react-based (version 16.14.0) PWA that is hosted on Microsoft Azure app service plans (premium tier). Tension: It is ONLY affects POST endpoints. GET endpoints successfully continue to work to these backends. Outcome: Current workaround is to change your app service to use http 1.1.

Dynamic product routes are not being generated statically (build shows only 3 pages instead of many) and navigating to a product on Vercel results in a 500 internal server error. The issue started after type changes in the products page code.

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