Postpone upgrading AAD Connect if you deployed Hybrid Azure AD join

Microsoft has reported an issue with Azure AD Connect 1.4.18.0 and Hybrid Azure AD joined devices. They recommend not deploying this version if you have deployed Hybrid AAD join.

1.4.18.0https://docs.microsoft.com/en-us/azure/active-directory/hybrid/reference-connect-version-history#14180

Warning

We are investigating an incident where some customers are experiencing an issue with existing Hybrid Azure AD joined devices after upgrading to this version of Azure AD Connect. We advise customers who have deployed Hybrid Azure AD join to postpone upgrading to this version until the root cause of these issues are fully understood and mitigated. More information will be provided as soon as possible.

This version has been removed from manual download until their incident investigation is complete. The latest version available now on the website is AAD Connect 1.3.21.0.

Details of the incident are not available, but if you have deployed AADC 1.4.18.0 and are experiencing problems, I recommend completely uninstalling AAD Connect and installing version 1.3.21.0.