Alphanumeric characters, dashes, underscores, spaces and slashes are allowed by default in user capability ID by default. This PHP regular expression is used: /[^a-zA-Z0-9_\-\s\/]/
Look if you have capability with 1 inside but containing not allowed characters. Let me know what it is.
I work on the export/import procedure upgrade. I will add the same filter to the export code in order do not generate this error if some existing capability does not go via this check.
