A repository ID can optionally include special chars like '@' (I don't think we ever actually restricted the allowed chars, explicitly). Such a repository ID can be created by the workbench, and the repository can be accessed and queried.
However, when executing a modification (such as a file upload , or a clear operation), A tomcat error page appears with the following error:
This error seems to be in the part of the workbench app that processes the server's response. As far as I can tell, the actual operation is executed correctly, but Workbench won't swallow the server response.
I have only tested with '@' (repository id: "firstname.lastname@example.org"), but this may be a broader issue with characters that need special treatment in URLs...