ICT operations security and operational policies, procedures, protocols, and tools are essential to ensure the confidentiality, integrity, and availability of data. One pivotal aspect is the strict separation of ICT production environments from the environments where ICT systems are developed and tested or from other non-production environments. That separation should serve as an important ICT security measure against unintended and unauthorised access to, modifications of, and deletions of data in the production environment, which could result in major disruptions in the business operations of financial entitiesas defined in Article 2, points (a) to (t) referred to in Title II of this Regulation. However, considering current ICT system development practices, in exceptional circumstances, financial entitiesas defined in Article 2, points (a) to (t) should be allowed to test in production environments, provided that they justify such testing and obtain the required approval.