When batch copying categories the folder names on the server are neither the alias of the original category nor is the configuration respected, e.g. "all lower case".
When I edit that copied categorie and do nothing else but just hit "save" the "Directory Name" changes to all lower case and spaces are substituted by _. But that does not change the folder name on the server. As a consequence now everything is messed up and an error occurs:
Error
Category folder name not found /var/www/virtual/.../(changed folder name)