AspNet Core using in memory repo for data protection when running in IIS

Those who are on the hosted environment where the access rights are very limited can use PersistKeysToFileSystem instead. Adding the following listing into the Startup.cs will resolve your issue:

public void ConfigureServices(IServiceCollection services)
{
    services.AddDataProtection()
    .PersistKeysToFileSystem(new DirectoryInfo(@"\\server\share\directory\"));
}

You can change the path string acording to your needs. Please also check ProtectKeysWith if you want to configure the system to protect keys at rest by calling any of the ProtectKeysWith* configuration APIs.

Data Protection keys used by ASP.NET applications are stored in registry hives external to the applications. When running your application as an AppPool Identity you have to create a registry hive for every AppPool used with an ASP.NET Core application.

For standalone IIS installations, you may use the Data Protection PowerShell script for each application pool used with an ASP.NET Core application. The keys will be persisted in the registry.

Like clearly stated in the logs since the registry hive that Data Protection looks for does not exist, keys will not be persisted to disk. Instead, they will be ephemeral and live in-memory only.

In web farm scenarios, an application can be configured to use a UNC path to store its data protection key ring. By default, the data protection keys are not encrypted. You can deploy an x509 certificate to each machine to encrypt the key ring.

See the official ASP.NET Core doc about data-protection for more information

User profile should be loaded in IIS configuration.

Open IIS, right click on Application Pools then Advanced Settings. And set "Load user profile" to true. Restart your app and it should work perfectly.