Running on-premises Dynamics 365? Think you're immune to cloud outages? Think again

Skype's tendrils spread to unexpected places

Hidden dependencies in Microsoft's on-premises Dynamics 365 can leave users open to cloudy outages.

Office 365 fell over for a few hours on 6 April in Europe and Asia, taking down anyone relying on Microsoft's cloud service. However, behind-the-scenes connections to Azure meant that those running on-premises versions were also potentially affected.

Dynamics 365 for Finance and Operations is Microsoft's Enterprise Resource Planning (ERP) suite aimed at medium to large companies. Customers reluctant to entrust data and processes to Microsoft's cloud have the option to purchase a licence to run the suite on their own hardware.

A Microsoft Developer Network article yesterday warned that users smugly pointing at their on-premises installation while their cloud-based colleagues struggled could well be subject to the same login problems, thanks to the gift that keeps on giving: Skype.

The issue is the Skype presence feature, which relies on an internet connection and makes a call to Azure Active Directory (AAD) when the user logs in.

Since AAD was also down on 6 April, the user was stuck and unable to get into systems that an administrator would be forgiven for thinking were not dependent on Microsoft's cloud.

The fix? There's a patch for that. The hotfix KB4091763 adds a switch to turn off Skype presence, which will stop external connections being made to Skype.

Customers who have invested in their own setup would be advised to consider flipping that switch to avoid their users being subject to the same vagaries as those living in the cloud.

The Register contacted Microsoft for further comment half a day ago and will update if a response to our questions is forthcoming. ®