Unable to sync with server. Violation for language value

I checked the default language of sugar by using App.lang.getLanguage(), which is 'en_us'.

Then I set it to 'en_uk' by App.lang.setLanguage('en_uk'). 

After doing this I am receiving this error "Unable to sync with server. Violation for language value".

I don't know why it is happening. I set it back to 'en_us' but still, it is happening. Please let me know how I can resolve this issue.