PaaS solutions have several potential disadvantages:
Concerns about data security: Some companies are hesitant to move their data storage off-site.
Challenges to integrating cloud solutions with legacy software: A company may need to support on-site solutions as well as cloud-based solutions. Communication between the two application types may be difficult or impossible.
Risk of breach by the PaaS provider: If the company providing the PaaS service fails to meet agreed-upon service levels, performance, security, and availability may be at risk, and moving the application may be difficult.