Update Octopus Server to .NET 9

[borland]

The enhancement

The Need

The Octopus Server is currently built using .NET 8. It packages a copy of the .NET 8 runtime.

.NET 9 is now available, bringing with it performance improvements, reduced memory consumption, as well as features our developers can use to write code more effectively.

Unlike the previous .NET 8 upgrade there is no support lifecycle reason forcing our upgrade; We elect to go to .NET 9 for the benefits it brings, and to reduce the risk of the future .NET 10 upgrade.

Solution

In 2025.1, Octopus Server has been upgraded from .NET 8. to .NET 9

We benchmarked roughly 30 common HTTP endpoints and .NET 9 is on average 15% faster than .NET 8

Note: While the Octopus Server bundles a copy of Tentacle, and deployment tools collectively referred to as Calamari, these are not being updated at this time. They will continue to use .NET 8 and/or the .NET 4.x Frameworks, and will be updated separately.