A system for the controlling of entrances comprises a plurality of access control units, wherein each entrance is allocated an access control unit with a data acquisition device assigned to it. The access control units are coupled to a control device via a network. An error signal is detected in the system which indicates that a first data acquisition device at a first entrance is not ready for operation and is unable to capture authorization data of a person wishing to gain access at the first entrance. A data signal is produced by a second data acquisition device at a second entrance, when the second data acquisition device captures the authorization data of the person wishing to gain access at the first entrance. In the system an activation signal is sent to the access control unit at the first entrance, in order to release the first entrance and grant the person access.