Azure AD connect is a tool developed by Microsoft to integrate on premise Active directory identities with Azure Active directory. This will enable on premise user to use the existing AD identity and credentials to access could applications such as Office 365.
Latest versions of Azure AD connect is 1.1.189.01 and this is released on (6/3/2016). You can download this from (here)

Symptoms

 After installing the AD connect and with password sync + password write back, event viewer will populated with following error after a Directory Sync.

The server encountered an unexpected error creating performance counters for management agent "testlocal.onmicrosoft.com – AAD".

This is not a critical error, this occur when performance counters cannot be loaded to the AD Sync. This can be resolved manually loading the performance counters.

Resolution

1. Stop the AD Sync Service - net stop ADSync
   
   
   
2. Backup the registry – select the ADsync key and export (this is for backup purpose, if anything goes wrong)
   
   
   
3. Delete the following registry key
   [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ADSync\Performance];
   
   
4. Re-create the registry key – Performance
   
   
   
5. Run the following commands
   unlodctr.exe ADSync
   lodctr.exe “C:\Program Files\Microsoft Azure AD Sync\Bin\mmsperf.ini”
   
   
   
   
   
6. Start the ADSync Service  - Net Start AdSync