I had a similar issue with my Vite-React app. The solutions listed below I believe directly relate to your issue.

ReactVite Express NodeJs Azure app service. 404 The resource you are looking for has been removed, had its name changed, or is temporarily unavailable

Run Express server with my NodeJS app via Azure App Service deployed to Azure Container

The physical path C:\Website\EDIConverterDemo\wwwroot\api\account\getcurrentuser You are only serving static files right now.

It does not look like a CORS issue either.

Overall, I think it is a config issue, The Physical path should be the routing file.

The app is deployed on IIS but where? On a VM or as an Azure Web App, this will be important as the target link and port config might change depending on the IIS environment.