api-ms-win-security-lsalookup-l1-1-0.dll - Analyze and How to Fix Errors

★★★★☆ Verified File (27.08.2026)

⚠️ Important Notice: API Security Library - File Description: api-ms-win-security-lsalookup-l1-1-0.dll provides essential security functions for lookup operations in Windows applications. Manually replacing system libraries can brick future Windows updates or cause critical system failures.

Architecture:	64-bit (x64)	Compatible with only 64-bit Windows
Creation date	14.07.2009 03:25:54
File version	6.1.7600.16385
Antivirus scan	✅ Clean	No viruses detected.
Digital signature	🟡 Not signed	Signature missing. The file may have been modified.
Hash Integrity	✅ MD5: Verified	File Hash protection is missing.
File size	3.5 kb.	3584 bytes.

Hashes:

MD5: 99c885a040571d5cc7b4497109bffe6e ✅
SHA-1: 549fd5735b729085aa6da0f6a4c6e4ce1ec59c1a
SHA-256: 47d2eb98891362ac82d5adda0d8d5c50e9cd7c1023bda5d4008371dbcb573cd9
SHA-512: ab3735577418b0cdc9f7c7b71a5c506bd2f80bbce488354eb548a7a17d2cb9feb688e5bf69e0426bbf87c50d94e536c748c8ee994a4e7fcc9d27c0c7af4a40ea

✅ This file is compatible with 64-bit Windows and ❌ will not work on a 32-bit operating system.

api-ms-win-security-lsalookup-l1-1-0.dll Guide

File Description

This file is a system DLL (Dynamic Link Library) module developed by Microsoft Corporation. It is part of the Local Security Authority (LSA) Lookup API, which handles the translation between user security identifiers (SIDs) and account names.

Standard File Location

The authentic file is located in the Windows system directories:

64-bit systems: C:\Windows\System32\ (64-bit version)
64-bit systems: C:\Windows\SysWOW64\ (32-bit version)

How to Fix the Error Without Downloading the DLL

Missing or corrupted DLL errors are usually caused by registry issues, malware, or corrupted system files. Follow these steps to fix the issue safely using built-in Windows tools.

1. Run SFC (System File Checker)

This tool scans and repairs corrupted Windows system files automatically.

Press the Windows Key.
Type cmd.
Right-click Command Prompt.
Select Run as administrator.
Type sfc /scannow and press Enter.
Wait for the scan to finish.
Restart your computer.

2. Run DISM (Deployment Image Servicing and Management)

If SFC fails to fix the files, DISM fetches clean copies from Windows Update.

Open Command Prompt as administrator.
Type DISM /Online /Cleanup-Image /RestoreHealth and press Enter.
Wait for the process to complete.
Restart your PC.

3. Install Pending Windows Updates

System DLLs are frequently updated and restored via official Windows packages.

Press Windows Key + I to open Settings.
Go to Update & Security (or Windows Update).
Click Check for updates.
Install all available updates.
Restart your machine.

4. Reinstall the Affected Program

If the error only happens when opening a specific app, that application's installation might be broken.

Press Windows Key + R.
Type appwiz.cpl and press Enter.
Find the problematic program.
Right-click it and choose Uninstall.
Reinstall the program from its official source.

📊 Diagnostics Tool: Verify Your `api-ms-win-security-lsalookup-l1-1-0.dll` File

Worried that the file on your PC has been modified by malware? Drop it into the form below. Our script will verify its file size, cryptographic hash (MD5/SHA-1), and check for a valid Microsoft digital signature.

Connected files:
API-MS-Win-Security-LSALookup-L1-1-0.dll
Other versions:
️ api-ms-win-security-lsalookup-l1-1-0.dll 6.1.7600.16385 32-bit (x86)