10000162 
Message
You cannot change the currency for a customer-type business partner linked to a sales order
Diagnosis
In the 
Business Partner
Business Partner Master Data 
path,
you have opened the Business Partner Master Data window
and you have added a customer-type business partner. You have created a sales
order for the business partner. In the Business Partner Master
Data window, you have attempted to update the business partner's
currency.
Procedure
You cannot update the currency for a customer-type business partner that is linked to a transaction.