# ERR\_SECURITY\_MUS\_USER\_UNMATCHED: The DSS user is not configured to be matched onto a system user[¶](https://doc.dataiku.com/dss/latest/troubleshooting/errors/ERR_SECURITY_MUS_USER_UNMATCHED.html#err-security-mus-user-unmatched-the-dss-user-is-not-configured-to-be-matched-onto-a-system-user "Permalink to this headline")

When DSS impersonates a user, it must have a rule to determine the system user name which it is supposed to impersonate. This error means no rule has been configured for this user.

## Remediation[¶](https://doc.dataiku.com/dss/latest/troubleshooting/errors/ERR_SECURITY_MUS_USER_UNMATCHED.html#remediation "Permalink to this headline")

This issue can only be fixed by a DSS Administrator.

Select an impersonation matching rule in the administation panel for the faulty user. See User Isolation Concepts for more information about identity mapping.
