Any time I try to set a user manually to be active on my forum through the admin panel, as well as adding them an avatar (when they request help with it), modifying a signature to be shorter, or anything else, really, I get this error and the change does not go through:

Template->make_filename(): Error - file error_body.tpl does not exist
I'm not completely convinced it relates only to user modification, though, as when I attempted to use the "Export" function for a style I had changed, I got the same error.

Any help on how to fix this is much appreciated. Thanks in advance.