We've been doing an automated deployment of upgrades, and have run into several instances of "Error 1719. The Windows Installer Service could not be accessed." appearing in the logs.
An example in the logs looks like this:
MSI (c) (AC:44) [05:09:30:008]: PROPERTY CHANGE: Adding EXE_CMD_LINE property. Its value is '/exenoupdates /forcecleanup /wintime 1649093056 /qn '.
MSI (c) (AC:44) [05:09:30:008]: PROPERTY CHANGE: Adding AI_IE_Ver property. Its value is '11'.
MSI (c) (AC:44) [05:09:30:008]: PROPERTY CHANGE: Adding AIEXTERNALUI property. Its value is '2'.
MSI (c) (AC:44) [05:09:30:008]: Doing action: AI_DpiContentScale
Action start 5:09:30: AI_DpiContentScale.
MSI (c) (AC:10) [05:09:30:008]: Invoking remote custom action. DLL: C:\Users\POSTGR~1\AppData\Local\Temp\MSI1B08.tmp, Entrypoint: DpiContentScale
MSI (c) (AC:D8) [05:09:30:008]: Cloaking enabled.
MSI (c) (AC:D8) [05:09:30:008]: Attempting to enable all disabled privileges before calling Install on Server
MSI (c) (AC:D8) [05:09:30:008]: Connected to service for CA interface.
MSI (c) (AC:10) [05:09:30:180]: Could not set proxy blanket on CA proxy interface. Error: 0x80070534
CustomAction AI_DpiContentScale returned actual error code 1601 (note this may not be 100% accurate if translation happened inside sandbox)
MSI (c) (AC:44) [05:09:30:180]: Note: 1: 1719
MSI (c) (AC:44) [05:09:30:180]: Product: NOP -- Error 1719. The Windows Installer Service could not be accessed. This can occur if you are running Windows in safe mode, or if the Windows Installer is not correctly installed. Contact your support personnel for assistance.
The sites in question are not in safe mode. Rerunning the upgrader has always resolved the issue, but this requires manual intervention. Are there any common causes of this issue, or any suggestions you can offer?