We have lots of clients using v13 to access many different files on a
v12 server. Everything has been OK except for one oddity. Pasting into
container fields is not working for two users. Other users with similar
software environments don't have the same problem.
Make sure you backup the php.ini file if you use cwp , been caught on that one. Save any server schedules and import them once you have fms13 up and running. After you have uninstalled FMS12, delete the filemaker server folder cause if you dont, deployment of 13 might fail.