The User Profile Service service failed the logon

I have received a Windows 7 machine where the user was unable to login to the system. Each time the user tried to login to the system he received the following error message:
The User Profile Service service failed the logon – User profile cannot be loaded. This was the only user on the system and it did not have a password set.

In order to solve this, I had to fix the profile issue using the registry editor in the Safe Mode.

Here are the steps on how to fix this issue:

Power ON the computer and hit F8 several times until you get the advanced boot options shown below:

Select Safe Mode and hit enter.

You should be able to log in normally into the safe mode. Once you are logged in open Registry Editor (regedit.exe) from the start menu.

Navigate to the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList

Here you will see several folders that are related to user and service profiles. Search for the 2 folders with longer names as you can see below:

The folder that is related to our profile has been renamed to ***.bak and the newly created folder above it has been related to the temporary profile we are currently using in the Safe Mode.

We have to rename the ***.bak folder to ***.aak and then rename the first folder to ***.bak and then remove the suffix from the ***.aak folder.

In the left pane select the folder without the suffix and in the right pane search for the keys RefCount and State.

Both keys should have their data set to 0. If they don’t, make sure you set the DATA value for both keys to 0. Please do not change the name or type of the key!

Close the registry editor and reboot. You should be able to log in normally now.

Comments are welcome.