Techniques are provided to permit a gradual or phased migration of a computing environment including groups of mobile clients to a new version of an application program such that the unavailability or downtime of any mobile client is minimized. In one general aspect, the techniques permit a mobile client to connect with an application server of the corresponding version for synchronization whether the mobile client is operating on the starting-version or the new or target-version of the application program and migrates the data between the two versions of the application program. A migration bridge between the starting-version and the target-version of the application program synchronizes the data in the two versions of the application program.