When synchronising  Active Directory isers on a server, to Azure Active directory you may receive errors saying there is a conflict:





To resolve this do the following:


  1. Ensure the user object in "on premise AD" has a proxy address attribute. The first address needs SMTP (in caps) and the additional addresses should have smtp (lowercase).  
  2. Go to the Azure Active Directory Connect Health page (https://portal.azure.com/#blade/Microsoft_Azure_ADHybridHealth/AadHealthMenuBlade/SyncErros)
  3. Select the user with the error
  4. Click Troubleshoot 
  5. Where it asks "Do both these accounts belong to the same user?" select "YES"
  6. Scroll to the bottom and select "Apply Fix"