Today, one of the my team member reported there are some issues with object syncing between on-premises to Office 365, when I checked Office 365 portal and found yellow highlighted warning under active user.
Immediately, I logged on my DirSync server and checked the events and found multiple event IDs related Directory Sync.
And same time open miisclient (C:\Program Files\Windows Azure Active Directory Sync\SYNCBUS\Synchronization Service\UIShell.) and found status stopped service down on delta import and Delta synchronization
From here I noticed all the “stopped-server-down” messages on the TargetWebService line.
After some digging I suspect the service account password could be main culprit for Sync.
I decided to update the service account password from within the Synchronization Service Manager
Management Agents-- > Right click TargetWebService--> Properties
finally re-set the password for service account.
After this, everything is working normal.