IT services are subject of several maintenance operations like upgrades, reconfigurations or redeployments. Monitoring those changes is crucial to detect operator errors, which are a main source of service failures. Another challenge, which exacerbates operator errors is the increasing frequency of changes, e.g. because of continuous deployments. In this paper, we propose a monitoring approach to detect operator errors in real-time by using complex event processing and anti-patterns. The basis of the monitoring approach is a novel business process modelling method, combining TOSCA and Petri nets. This model is used to derive pattern instances, which are input for a complex event processing engine in order to analyze them against the generated events of the monitored applications.