We are in the process of upgrading all exchange server to service pack 2. Out topoligy is this we have 1 front end server which is our gateway. It in turn router to the city servers via routing groups. One of the city server was brought up to SP2 before the front end. So now users in that city are not able to get to outlook web access. Frist has any one seen this and is there a fix. Second can I upgrade the front end server and fix this issue, or do I have to upgrade all servers, or rebuild the one that was upgraded by mistake??