Hi,
I meet to the same question,I use ArcGIS for Server 10.2 of English edition,But I want to get route directions in Chinese,So I set the parameter languages direction to "zh-CN" when solving the route,Then I get the error "Unable to complete operation.Solve required prior to generating directions."
I asked Esri for Help ,But they advised me to setup Chinese edition in order to return Chinese language,I couldn't believe it ,I have many services in my server ,It will cost plenty of time ,Isn't there other solution?