What Is Hkey_users S-1-5-21?

The Windows Registry is an essential component of the Microsoft Windows operating system. It is a hierarchical database that stores configuration settings and options for Windows, as well as for applications installed on the system. One of the keys in the registry is the HKEY_USERS key, which is where user-specific data is stored.

Within the HKEY_USERS key, there are various subkeys and values, including one with the identifier S-1-5-21. This identifier refers to a particular security identifier (SID), which is a unique alphanumeric code assigned to each user account, group, and computer on a network. In this article, we will delve deeper into what the HKEY_USERS S-1-5-21 subkey is, what information it contains, and why it is critical for Windows system administrators.

Understanding hkey_users s-1-5-21

HKEY_USERS S-1-5-21 is a registry key in the Windows operating system. Here’s a more detailed explanation:

– The Windows registry is a database that stores configuration settings for the operating system and applications installed on a computer.
– The HKEY_USERS registry key contains subkeys that correspond to each user profile that has logged onto the computer.
– Each user profile is identified by a security identifier (SID), which is a unique alphanumeric string that represents the user account.
– The SID for the current user account is stored in the HKEY_CURRENT_USER registry key.
– The SID for the built-in administrator account is always S-1-5-21--500, where is the name of the computer or domain.
– The HKEY_USERS S-1-5-21 key refers to a specific user profile based on its SID.
– It is possible to view the registry settings for a specific user profile by navigating to the HKEY_USERS S-1-5-21 key and selecting the appropriate subkey.
– This can be useful for troubleshooting or configuring settings for a specific user account.
– However, editing registry settings can be risky and should only be done by experienced users or IT professionals.
– It is also important to make a backup of the registry before making any changes to ensure that the computer can be restored if there are any issues.


1. What is HKEY_USERS S-1-5-21?
HKEY_USERS S-1-5-21 is a specific registry key in Microsoft Windows that contains information about user profiles that are currently loaded in the system.

2. What is the significance of S-1-5-21 in HKEY_USERS S-1-5-21?
S-1-5-21 is a unique Security Identifier (SID) assigned to a particular user or group in a Windows domain network. It helps Windows to identify and manage user accounts and permissions.

3. Can HKEY_USERS S-1-5-21 registry key be deleted?
Yes, you can delete HKEY_USERS S-1-5-21 registry key if you want to remove specific user profiles from the system. However, it is recommended to create a backup of the registry before making any changes.

4. How can I access HKEY_USERS S-1-5-21 registry key?
To access HKEY_USERS S-1-5-21 registry key, you need to open the Registry Editor on your Windows computer. Navigate to HKEY_USERS folder, and look for the subkey with the corresponding SID (S-1-5-21).

5. What information is stored in HKEY_USERS S-1-5-21 registry key?
HKEY_USERS S-1-5-21 registry key stores information about user profiles, including user account data, desktop settings, application configurations, and other related information. This key is crucial for maintaining user preferences and settings on a Windows system.


In conclusion, we have explored the significance of the HKEY_USERS S-1-5-21 in Windows Registry and its importance in managing user profiles and settings on a computer. This registry key holds crucial information pertaining to user accounts and their settings, allowing for efficient and effective management of user profiles on a Windows system. Understanding the HKEY_USERS S-1-5-21 registry key is essential in troubleshooting and resolving potential issues related to user profiles on your computer. So, the next time you encounter an issue with user profiles on your Windows system, keep in mind the significance of the HKEY_USERS S-1-5-21 registry key.

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