Fix Error 18456 Free--Step by Step Solution to Fix Windows Error 18456 (Windows 7, Vista and XP)

Error 18456 is related to Windows Authentication and SQL. Following are the simple troubleshooting instructions that worked for many people all over the world.

Troubleshooting Guidelines:

  • 1) Enable Security Administrators and Database Creators Server Roles
  • 2) Repair SQL Registry Entries
  • 3) Enable SysLogin and Public Server Roles
  • 4) Clear Temporary Files
  • 5) Scan your System

Compatible with Windows 7, Vista and Windows XP

Enable Security Administrators and Database Creators Server Roles:

  • 1) Launch SQL Server Enterprise Manager.
  • 2) Expand Microsoft SQL Servers | SQL Server Group | | Security.
  • 3) Right click the option “Logins” and select “New Login”.
  • 4) In the Name field, type the name of the account you wish to log-in. Make sure that your log-in name is in the following format:
  • 5) DomainName\AccountName
  • 6) Click “Server Roles” tab.
  • 7) Mark the check boxes “Security Administrators” and “Database Creators” as checked.
  • 8) Click OK button.
  • 9) Exit SQL Server Enterprise Manager.

Repair SQL Registry Entries::

Problems with the registration of SQL Server Enterprise can be the reason behind error 18456 in Windows 7, Vista and XP. Repair the entries to fix your problem. Download a Registry Cleaner and PC Optimizer software. Start a full registry scan. Repair the problems found in it.

Enable SysAdmin and Public Server Roles::

Error 18456 appearing with Windows Authentication in Windows 7, Vista and XP can be solved by changing the server roles and reconfiguring some settings. The required steps are:

  • 1) Log-in using the SA User Name and Password that you have.
  • 2) Expand the following:
  • 3) SQL Authority | Security.
  • 4) Right click “Logins” and select “New Login” option.
  • 5) Type the valid user name, for example, SQLAuthority\Vikas
  • 6) Click “Server Roles”.
  • 7) Mark the checkboxes called “SysAdmin” and “Public” as checked.
  • 8) Click OK.

Clear Temporary Files::

Deleting the temporary files may fix error 18456. Using a System Cleaner application or the Disk CleanUp utility, delete temporary files as shown here:

  • 1) Click Start | All Programs | Accessories | System Tools | Disk CleanUp.
  • 2) Select a disk and press ENTER.
  • 3) Follow the on screen instructions.

Scan your System::

Using a good antivirus software with up-to-date virus definitions, scan your system for viruses and remove all the infections found.