The LsaLookupSids function may return the old user name instead of the new user name if the user name has changed

This article describes a cache update delay in Windows.

Original KB number:   946358


Consider the following scenario:

  • On the domain member computer, an application calls the LsaLookupSids function to translate a security identifier (SID) to a user name.
  • The user name has been changed on a domain controller.

In this scenario, the LsaLookupSids function may return the old user name instead of the new user name. This behavior may prevent the application from working correctly.


The local security authority (LSA) caches the mapping between the SID and the user name in a local cache on the domain member computer. The cached user name isn't synchronized with domain controllers. The LSA on the domain member computer first queries the local SID cache. If an existing mapping is already in the local SID cache, the LSA returns the cached user name information instead of querying the domain controllers. This behavior is intended to improve performance.

The cache entries do time out, however chances are that recurring queries by applications keep the existing cache entry alive for the maximum lifetime of the cache entry.


To work around this issue, disable the local SID cache on the domain member computer. To do this, follow these steps:

  1. Open Registry Editor.

    To do this in Windows XP or in Windows Server 2003, click Start, click Run, type regedit, and then click OK.

    To do this in Windows Vista and newer, Click Start, type regedit in the Start Search box, and then press ENTER.

  2. Locate and then right-click the following registry subkey:

  3. Point to New, and then click DWORD Value.

  4. Type LsaLookupCacheMaxSize, and then press ENTER.

  5. Right-click LsaLookupCacheMaxSize, and then click Modify.

  6. In the Value data box, type 0, and then click OK.

  7. Exit Registry Editor.


The LsaLookupCacheMaxSize registry entry sets the maximum number of cached mappings that can be saved in the local SID cache. The default maximum number is 128. When the LsaLookupCacheMaxSize registry entry is set to 0, the local SID cache is disabled.


The behavior is by design.

More information

The LSA maintains a SID cache on domain member computers. This cache stores mappings between SIDs and user names. If the SID information exists in the local cache, the LSA returns the cached user name information instead of checking whether the user name has changed.

The local SID cache helps reduce domain controller workload and network traffic. However, inconsistency may occur between the local cache and the domain controllers.


TechNet has an article that covers Sid-Name resolution approaches, including a detailed description of this cache:

How SIDs and Account Names Can Be Mapped in Windows

For more information about the LsaLookupSids function, visit the following Microsoft Web site:

LsaLookupSids function