I'm getting the following error:

   Core Localization File Not Found: : ~/App_GlobalResources/GlobalResources.en-US.resx

I thought the default resources e.g. ~/App_GlobalResources/GlobalResources.resx were the US ones?

Certainly I've never seen this resource file.

Any ideas?

Thanks,

Not sure what you mean by a fallback language - I've enabled both US & GB English (I've installed the GB language pack). GB English is the portal default. Unfortunately the error doesn't give any hint of what was actually happening at the time it happened. So I don't know which page it happened on or anything else about it.

Actually it always seems to happen after adding or removing a user - so maybe that is related.

Think you might be onto something there! ;)

<?xml version="1.0" encoding="UTF-8"?>
<root>
  <language name="English" key="en-US" fallback="" />
  <language name="English (United Kingdom)" key="en-GB" fallback="en-US" />
</root>