We are performing an estate wide in place upgrade using SCCM version 1909 to Upgrade Windows 10 1809 x64 to Windows 10 1909 x64.
The issue were seeing is that in a disconnected upgrade scenario (Wireless or VPN) the task sequence will fail with the error “Timed out waiting for CcmExex service to be fully operational” (misspelling intentional) for any application steps post upgrade.
The task sequence resumes and proceeds but Setupcomplete.bat doesn’t seem to receive an exit code from TSMBootstrap.exe. If you modify Setupcomplete.bat to allow command prompt access you can see the CCMexec service is running but the task sequence will not detect this.
This is causes by having a Cloud Management Gateway that is unreachable. If you look in the location services log you see it repeatedly trying to connect to the CMG despite having no network connection (or unreachable), this continues indefinitely until timeout. Microsoft Support have stated this is not a supported scenario (a task sequence must be able to see at least one Management Point). Microsoft won’t confirm this as a bug despite this also being an issue that previously affected standalone media, and which has subsequently been fixed.
To workaround this issue you must ensure any steps post upgrade do not rely on the CCMExec service (Install application or install package). These are limited to Run Command Line or Run PowerShell script steps. The simplest method is to create a package that references the same source directory as your original application and replicate the programs command line.