Directories and/or folders can contain single parts which are part of an assembly. In this case the assembly must also "receive" a new directory name. Otherwise the assembly can no longer "find" the single part and therefore the assembly can no longer be assembled.

Therefore, activate the option field Customize links in assemblies [Adapt links in assemblies] for assemblies and enter the path of the assemblies [Assemblies path] (Browse ... ) in which the assembly is located. Please bear in mind, however, that this process may take a long time!

I case you have not yet saved changes made within a directory tree, first the Save All window shows up. Save the desired changes before you rename the directory.