Knowledge base

Knowledge base: Error Messages
An authentication error occurred. See the server error log for details

This article applies to the following product(s):

VNC® Enterprise Edition/VNC Personal Edition


This error is usually received because the Application Event Log of the VNC Server machine you are trying to connect to is full. When using Windows authentication, VNC needs to be able to log the authentication to the Event Log for auditing purposes.


On the VNC Server machine, please navigate to the following location:

Control Panel > Administrative Tools > Event Viewer > Application

Right click on the Application Log and select 'Clear Events'. To prevent this from happening again, you can enter the log properties and select 'Overwrite as needed'.

If this issue is not resolved by clearing the Application Event Log, then it may be a "Local Group Policy" issue. Please check your Local Group Policy settings, and ensure that "Everyone" has the option "Access this computer from the network" enabled:

  1. Run "gpedit.msc"
  2. Navigate through Computer Configuration > Windows Settings > Security Settings > Local Policies > User Rights Assignment
  3. Double click on "Access this computer from the network", and ensure "Everyone" is added.