Culture 'en' is a neutral culture. It cannot be used in formatting and parsing and therefore cannot be set as the thread's current culture.

The following exception may be thrown when trying to open a log file in the Sitecore Log Viewer:

“Culture ‘en’ is a neutral culture. It cannot be used in formatting and parsing and therefore cannot be set as the thread’s current culture.”

To overcome this, open the User Manager and add a value in the RegionalIsoCode field for the user affected. For GB English, enter en-GB.