Enterprise software systems across highly regulated and technology-intensive industries are undergoing profound transformation as organizations confront the limitations of legacy architectures in the context of cloud computing, continuous delivery, and platform-driven innovation. Over the past two decades, monolithic application frameworks, tightly coupled infrastructures, and on-premises deployment models have constrained scalability, security responsiveness, and organizational agility. In response, cloud-native paradigms, microservices architectures, container orchestration platforms, and framework-level evolutions such as the transition from ASP.NET to ASP.NET Core have emerged as foundational enablers of modernization. This research article develops a comprehensive theoretical and analytical examination of enterprise application modernization, with a particular focus on architectural evolution, tooling ecosystems, migration strategies, and governance challenges associated with cloud-native adoption.

Drawing strictly on the provided scholarly and industry references, the article positions the evolution of ASP.NET to ASP.NET Core as a representative case of framework-level modernization that reflects broader shifts toward modularity, cross-platform execution, container compatibility, and DevOps alignment (Valiveti, 2025). The analysis situates this evolution within a wider landscape of microservices research, Kubernetes adoption, intelligent cloud management, zero-downtime deployment strategies, and security-preserving migration methodologies (Shadija et al., 2017; Shamim et al., 2022; Nilsson, 2018; Mantri, 2019). Through an extensive interpretive methodology grounded in qualitative synthesis, the study examines how architectural decisions interact with organizational constraints, regulatory environments, and operational risk profiles, particularly in sectors such as banking and insurance (Bhattarai, 2020; Madasamy, 2022; Milne et al., 2020).

The results articulate a layered model of modernization outcomes, emphasizing architectural decoupling, deployment resilience, governance automation, and security-by-design as emergent properties of successful transformation initiatives. Rather than treating modernization as a purely technical refactoring exercise, the article demonstrates that sustainable outcomes depend on alignment between framework capabilities, orchestration platforms, testing modernization, and institutional governance mechanisms (Kesserwan et al., 2018; Taibi et al., 2018). The discussion advances a critical perspective on unresolved tensions in cloud-native adoption, including operational complexity, skills fragmentation, and regulatory opacity, while proposing future research directions that integrate intelligent automation and policy-aware infrastructure.

By providing an in-depth, theory-driven, and citation-grounded analysis, this article contributes to the academic discourse on enterprise software modernization and offers a cohesive conceptual foundation for scholars and practitioners navigating the evolving intersection of legacy systems and cloud-native architectures.