User Profile Service service failed the logon. The user profile cannot be loaded.

While logging in to server "User Profile Service service failed the logon. The user profile cannot be loaded" error will be displayed. 

This may occur due to various reasons like duplicate SIDs, corrupted registry, corrupted user profile. The following are the eventlogs that will be generated in application logs:

**************************
Log Name:      Application
Source:        Microsoft-Windows-Winlogon
Date:          9/18/2012 1:02:34 PM
Event ID:      6001
Task Category: None
Level:         Warning
Keywords:      Classic
User:          N/A
Computer:      xyz.abc.com
Description:
The winlogon notification subscriber <Profiles> failed a notification event.
===================

Log Name:      Application
Source:        Microsoft-Windows-Winlogon
Date:          9/18/2012 1:02:34 PM
Event ID:      6001
Task Category: None
Level:         Warning
Keywords:      Classic
User:          N/A
Computer:      xyz.abc.com
Description:
The winlogon notification subscriber <Sens> failed a notification event.
==================

Log Name:      Application
Source:        Microsoft-Windows-Winlogon
Date:          9/18/2012 1:02:06 PM
Event ID:      6004
Task Category: None
Level:         Warning
Keywords:      Classic
User:          N/A
Computer:      xyz.abc.com
Description:
The winlogon notification subscriber <Profiles> failed a critical notification event.
==================

Log Name:      Application
Source:        Microsoft-Windows-User Profiles Service
Date:          9/18/2012 1:02:06 PM
Event ID:      1500
Task Category: None
Level:         Error
Keywords:      Classic
User:          abc\ghouse
Computer:      xyz.abc.com
Description:
Windows cannot log you on because your profile cannot be loaded. Check that you are connected to the network, and that your network is functioning correctly.

 DETAIL - The system cannot find the file specified.
 
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To fix this issue, you can follow the below link:

http://www.vistax64.com/tutorials/130095-user-profile-service-failed-logon-user-profile-cannot-loaded.html


If you are still not able to login or getting the same error then it would be probably due to the corrupted "Default" profile (C:\Users\Default) getting corrupted and can be fixed by copying the "Default" user profile from other working server.

To do this, follow the steps:

1) Login the server and move C:\Users\Default folder to other location. (This is just to put as a backup copy of folder ).
2) Copy the C:\Users\Default folder from other server having the same Windows OS and paste it in the problematic server at same location.

This should fix the issue. If the issue still persists, please reboot the server and try to login.