Boot failed: Umbraco cannot run

Questions
1

Dear all,
i’ve just installed umbraco 8.3 on my local machine without any problems. If i try to start it from Visual studio it works fine but, after configure it on my local IIS if i try to navigate it i get:

    Boot failed: Umbraco cannot run. See Umbraco's log file for more details.

-> Umbraco.Core.Exceptions.BootFailedException: A connection string is configured but Umbraco could not connect to the database.
  in Umbraco.Core.RuntimeState.DetermineRuntimeLevel(IUmbracoDatabaseFactory databaseFactory, ILogger logger) in D:\a\1\s\src\Umbraco.Core\RuntimeState.cs:riga 194
  in Umbraco.Core.Runtime.CoreRuntime.DetermineRuntimeLevel(IUmbracoDatabaseFactory databaseFactory, IProfilingLogger profilingLogger) in D:\a\1\s\src\Umbraco.Core\Runtime\CoreRuntime.cs:riga 259
  in Umbraco.Core.Runtime.CoreRuntime.Boot(IRegister register, DisposableTimer timer) in D:\a\1\s\src\Umbraco.Core\Runtime\CoreRuntime.cs:riga 149

Thanks in advace
Davide

This is a companion discussion topic for the original entry at https://our.umbraco.com/forum/99949-boot-failed-umbraco-cannot-run