For a long time, Azure Key Vault was not following the same API versioning scheme as other Azure services. If you’ve used the Azure Key Vault Emulator ever since I forked the old (very limited) code, You’ll have noticed that the APIs the emulator implemented were from the v7.4 definition. After that, Microsoft published a v7.5 and v7.6 version. For example, v7.6 introduced an API for getting key attestation.

Sometime last year, they must have decided to align API versions with other Azure services, and they switched to the date-based versioning. The first new such version they introduced was 2025-07-01, and one of the new things they added was the outContentType parameter on the Get Secret APIs.

I had wanted to add support for more recent API versions for a while, so used the new versioning scheme as a motivator to get going with this. Specifically, the latest emulator release, v2.2.0 has support for API versions v7.4 through v7.6 and the latest 2025-07-01, though it’s important to point out that not all APIs are fully supported, like before. Sadly, specifically the above-mentioned newly introduced APIs (key attestation and secret output content type) are not yet supported. This new release however is tested against all API versions supported by the emulator: the tests are run with a recent version of the SDK for Key Vault but switching versions as needed.

Also, with the additional build infrastructure added, it is now relatively easy to create a build that’s targeting only a specific API version should that ever be required. Adding support for new API versions should also be easier. As a cherry on top, it should also be a lot easier now to enforce API verions in the emulator. This is not implemented yet, but if there’s a need/desire to have it, please open a new issue describing your needs, and I’ll see to get this addressed in a timely manner.