When upgrading Files from version 3.8.1.3 to 4.1.0.2 for all dark sites, the File Server Module component needs to be upgraded alongside the core Files components. This is because the File Server Module is a core component of Files and is responsible for file-level data services, including access control, auditing, and file sharing.

If the File Server Module is not upgraded alongside the core Files components, it can result in compatibility issues and potentially cause the upgrade to fail.

Therefore, it is recommended to upgrade the File Server Module together with the core Files components when upgrading Files.