Azure AD Connect Syncronization Service not Installing

Question

Please help assist: After updating AzureAD Connect, the installation failed and we were told that uninstalling and reinstalling would fix immediately. Unfortunately, it made matters worse because at least we could manually sync. Now I'm stuck and needing to onboard users.

Answer 1

Check first to make sure that the all of the credentials you have entered in the wizard and that you are using domain\user and not domain.com\user as the format (since that's what the app takes).

If that doesn't work, you need to also make sure you have an account with local administrator privileges on your computer to install Azure AD Sync. Then, during the Azure AD Connect installation you will be asked for two credentials - an enterprise admin account for the on-premises DC and a Global Admin account for the Azure AD cloud tenant that you are syncing to.

If you already have the right credentials, step through all the keys in

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products\
Look for the one with Product Name Microsoft Azure AD Connect . Delete this and restart the installer.

Also, if the keys below exist, remove them:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products\7EC08CB7BBBDF1045B31147D9AC698FB

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products\E2D094C21044C254D9583B64140ED511