Microsoft is about to make a potentially breaking change affecting the Azure Service Fabric runtime - due to an unspecified security issue - that could impact those still running on unsupported versions.
The fix for the security issue will see an impact to all service fabric clusters on versions 5.7 (support ended at the close of 2017) to 6.3.63.* (which saw its support come to an end on 3 March 2019) and Microsoft, naturally, is keen that users upgrade. This means a leap to the sunlit uplands of version 7 if support is required.
"We observed some customers have not taken action to avoid outage to clusters," intoned Microsoft.
However, not all users are that keen on the pace of development and there are the odd breaking changes between versions. Service Fabric 7.2, for example, dropped support for.NET Core Service Fabric apps running with the .NET Core 2.2 runtime (itself, admittedly, out of support in 2019).
While large chunks of the Azure infrastructure were built using Service Fabric, developers have been lured in recent years to container orchestrators such as Kubernetes.
Although not directly comparable (the "cloud native" approach of the latter could be regarded as at odds with the distributed application server approach of the former), Service Fabric has continued to evolve regardless. Indeed, bits of Microsoft's own take on Kubernetes, the Azure Kubernetes Service (AKS), runs atop the technology.
Those who have thrown their lot in with the tech, but have left things well alone once up and running, should therefore check their versions. To quote Microsoft: "Service Fabric clusters will not come up if you have not upgraded." ®