You are moving a customized SharePoint site collection to a new farm. You attach and mount the source content database in the destination farm. You need to ensure that all customizations from the…

Custom SharePoint applications, solution packages (.wsp files), and features are deployed at the farm level and are not transferred with the content database. Installing all custom applications in the destination farm ensures the farm has the required features and assemblies to render and execute any custom code referenced by the migrated site collection. Without this step, pages or features dependent on custom solutions will fail to load.

Copying master pages to the Style Library does not make them functional, as customizations may depend on custom features, web parts, or solution assemblies that must be installed at the farm level.

SharePoint groups and user permissions are stored in the content database and are already migrated with the database attach; manually copying them is unnecessary and does not address missing customizations.

Master pages from a source site collection may already be in the content database, but without the underlying custom features and assemblies installed on the farm, copying master page files alone will not restore full functionality.