ExcelService issue

Hi All,

We have one portuguese variation in our application and suddenly user getting the below error while opening the page. 

UI culture Portuguese(Brazil)(pt-BR) is not supported.UI culture English (United States) (en-US) is being used instead.

Click OK to view the workbook using UI culture English(United States)(en-US).

The language pack already installed for this version but don't know exact issue.

Please help me on this issue.

Regards,
Kumar