Recently I've created an account on oracle cloud and created a autonomous database processing, i have a simple .NET Core API, she connect on my cloud database using EF Core and returns select result in JSON format, on localhost works normally, my application was connect to database and returns my expected result. When i publish the application on azure web app free plan, the application doesn't connect to my autonomous database, i think because i'm trying using a free plan, someone just tried do something? (Oracle Cloud + Azure Web APP)
It is possible that you are hitting the Azure Web App's sandbox restrictions. Some tips to troubleshoot:
Take a look at the documentation on this topic and see if it applies to your web app, https://github.com/projectkudu/kudu/wiki/Azure-Web-App-sandbox
Check if you can find the any errors via App Service Diagnostics, https://azure.github.io/AppService/2018/09/24/Announcing-the-New-App-Service-Diagnostics-Experience.html