Due to a mistake on my site I received the following error message:
Got error 'empty (sub)expression' from regexp
When I log off, logon again and try the userlist again, this message persists. Also updating to the latest version, does not resolve this.
In the address line the following (last part) of the address is: administrator/index.php?option=com_comprofiler&view=showusers

Any suggestions how to remove this error?

thanks in advance, Hugo

After about 5 hours, the issue resolved itself