Hello @Axel GLEIZES
Welcome to Microsoft Q&A Forum, thank you for posting your query here!
As per my understanding, you're unable to register the Azure File Sync agent in a Windows Server 2016 machine.
Usually, this error may be caused due to some updates missing. Did you check if you have the following ones installed?
- Windows Server 2012 R2: KB5021653
- Windows Server 2016: KB5040562
- Windows Server 2019: KB5005112 and KB5040430
For reference: https://learn.microsoft.com/en-us/azure/storage/file-sync/file-sync-deployment-guide?tabs=azure-portal%2Cproactive-portal
Please, feel free to tag me if you have further questions.
Have a great week ahead.