Sometimes, Windows 10 or earlier editions demonstrate a message like this:
In most cases, this is a Windows registry problem. Besides preventive methods such as regular registry backup, these are some solutions for this problem.
Fixing Windows Logon
Firstly, start Windows at safe mode. (The most convenient way to do it is to shut down your PC physically and then select safe boot in Windows starting menu when rebooting.)
Then open the utility. To do it, just press a Windows logo button and the "R" key simultaneously, and type "regedit" in a command prompt window.
In a registry editor, use the tree navigation to open the section called
HKEY_LOCAL_MACHINE / SOFTWARE / Microsoft / Windows NT / CurrentVersion / ProfileList
Here are the two cases to fix.
Case 1: Spontaneous Backup
If some registry folder named "S-1-5" and your account name has a ".bak" extension, and other has no such addition, this may be a case of your problem. Rename these both folders to swap extensions.
- Rename the folder without a ".bak" extension by adding some extension (except ".bak") to it.
- Remove the ".bak" extension from a folder that already contains it.
- Change an extension of a first folder to ".bak". That is all!
Case 2: Insufficient Registry Keys
If you have only one folder in a registry related to your account, and this folder has a ".bak" extension, you will need to change keys in this folder to make it working properly.
- Remove the ".bak" extension from this folder name.
- Change the value of the "RefCount" key in this folder to zero.
Note: If you have no such key, create it as a DWORD type and initialize it with 0.
- Make the same operation with the "State" field in this folder.
After making these changes, close the registry editor and restart your machine in a default mode. This will fix your problem with Windows 10 user logon.
Causes of User Logon Problems
The main cause of these problems is incorrect user removal. When you delete a user manually, his or her SID is still active in a system, causing logon problems and persisting by many other ways in a system, including causing a weak point for backdoor vulnerabilities.
An advice: Always use a defined procedure to remove user by an "Advanced System Settings" menu!