12.9 Upgrading to Version 13 using JIT Upgrade
The first step is to upgrade the Application Server to Version 13. It will continue to provide V12 Package upgrades to the V12 clients until a V13 Application is created and set up. It is critical that the Application name of the V13 Package is the same as the V12 Package. This will occur automatically if you convert your V12 Application to V13 using the feature provided in the Deployment Tool. Refer to Convert a Pre-V13 Template for more information.
When the MSI file has been placed in the correct location, the next time the V12 Client connects, the V13 server will detect that a V13 Package is available and download that. It will no longer download V12 packages.
Behind the scenes, the V13 server always supplies a SETUP.EXE to the client that executes the MSI file. This allows for customization of MSI parameters, but is crucial to the V12 Client being able to install the V13 Package. This is because the V12 Client only executes SETUP.EXE. Further, if the Client is V12, then the file x_apps\<Application name>\boot\cab2\build.dat is transferred to the Client. This causes the V12 Client to execute SETUP.EXE because the build number inside (e.g. 4051) is later than the one the Client is using (for example 4050).