Preflight response is not successful
You should add the address of your requesting site URL in CORS in your Server/Backend code. Each language or framework might have their own way of adding this, try to search "[backend language] cors" (e.g. "C# cors") in google. (credits to @Gary Liu - MSFT)
You can confirm you have added correct origin by inspecting network tab in developer's console.
First select the request with method OPTIONS
Then verify the Access-Control-Allow-Origin is the same with your Origin
How about setting up a proxy instead?
proxy.config.json
{ "/api/contacts" : { "target": "http://{{webapp name}}.azurewebsites.net/api/contacts", "secure": "false, "changeOrigin": true, "pathRewrite": { "^/api/contacts/": "" } }}You can find more details on https://angular.io/guide/build#proxying-to-a-backend-server