Evidence note

Incidents During Microservice Decomposition: A Case Study

Peer-Reviewed Research2025Carbon Health, EASE 2025

What was examined?

A production case study of a healthcare technology company's multi-year decomposition of a monolithic application into a hybrid architecture involving modularisation and more than 20 microservices.

107 production incidents analysed from June 2020 to February 2025.

Key findings

1The transition was incremental rather than a single cutover.
2The organisation used progressive traffic routing and compared old and new implementations before removing existing behaviour.
3A substantial portion of the product remained in the monolith while selected capabilities moved to microservices.
4New categories of production problems appeared as the architecture changed.
5Modularising the remaining monolith was identified as an important part of the transformation.
6Data migration introduced performance and consistency challenges.

Why it matters. Lornets interpretation.

Migration changes the risk surface rather than simply removing risk. Hybrid and modular states can be legitimate engineering outcomes, and data transition, verification and decommissioning are part of the migration itself.

This is the Lornets reading of the source, not a finding of the source itself.

What it does not establish

1This is one healthcare organisation.
2Team size, pandemic-period workload and incident-reporting practices changed during the study.
3Its incident counts should not be interpreted as universal microservice failure rates.