From Control Panel, I set my Region and Language setting to French (France)
When I am running my application as console application,
Thread.CurrentThread.CurrentCulture returns French
But when I'm running it as windows service, it returns invariant culture or English (US)
Is there a way to fix that?
The service is probably running as a user that has it's own culture.
Why not set the culture when you start your service
Thread.CurrentThread.CurrentCulture = new CultureInfo("fr-FR");
Thread.CurrentThread.CurrentUICulture = new CultureInfo("fr-FR");
Also from Default Culture in a Windows Service
If your Windows Service is running under the SYSTEM account or other account without a
profile it will use the settings defined under the
"HKEY_USERS/.DEFAULT/Control Panel/International" registry key.
You can change these values from "Control Panel / Regional and Language Options / Advanced"
by checking the checkbox "Apply all settings to the current user account and to the default
user profile".
I normally use the former technique as I only need to change it for a specific service rather than for the whole OS.
.NET 4.5 added CultureInfo.DefaultThreadCurrentCulture and CultureInfo.DefaultThreadCurrentUICulture i suggest setting it as early as possible and it should solve your issue.
This will change the current threads culture and all threads that are created.
来源：https://stackoverflow.com/questions/26474132/windows-service-unable-to-get-correct-system-culture