We were in the middle of a few upgrades to Sitecore 10.4 when Sitecore 10.4.1 was released on June 25th 2025. I used the Sitecore Install Assistant to install Sitecore 10.4.1 rev. 012149 (Setup XM1 Developer Workstation rev. 1.6.1-r7).

Usually I install a plain vanilla that I use for comparison and one instance where I work on the upgrade. Both the installs completed successfully. I was also able to load the instances.

When I tried to login to the admin, I was seeing an error.

The worst part is there are no logs generated in the Identity server and there are no error log entries in the Sitecore logs either.

If we disable the Sitecore Identity Server, it works fine but doing this causes other issues and it does not match up with the upstream environments.

My smart friend Kamruz then discovered the following in the developer documentation:

2.8. Encrypted communication with SQL Server

New versions related applications might require encrypted communication with SQL Server, for example Sitecore Identity Server module version 8.0 and later, and Sitecore Publishing Service version 8.0 and later. This change is due to the adoption of a newer version of Microsoft.Data.SqlClient that enforces increased security, as described in Microsoft’s Breaking changes in EF Core 7.0 article.

To configure encrypted communication with SQL Server:

1. Configure an encryption certificate on SQL Server. A valid encryption certificate must be installed and configured on SQL Server to support encrypted communication. For more information refer to Microsoft’s Configure SQL Server Database Engine for encrypting connections article.

2. Ensure the certificate is trusted on the server hosting the Sitecore application.

3. (Optional) Enforce the Sitecore application to use an encrypted connection to SQL Server.

Update the connection string of the Sitecore databases to add the following parameters:

Encrypt=true;TrustServerCertificate=false;

For example:

<ConnectionString>
Data Source=.;Initial Catalog=Sitecore.Core;User ID=coreuser;Password=Test12345;Encrypt=true;TrustServerCertificate=false;
</ConnectionString>

This configuration ensures encrypted communication with SQL Server while enforcing strict certificate validation.

You have to update the \inetpub\wwwroot\SCVanilla10.4.1identityserver.dev.local\Config\production\Sitecore.IdentityServer.Host.xml and add the Encrypt=false; on your local to work. You could also setup the encryption on your local and set it to true as well.

Once this is done, reset IIS and try again. Welcome to Sitecore 10.4.1!