There are a few breaking changes to the hosting model of the Windows Services in Dime.Scheduler 2021.1.0. In order to be able to run the services, you need to remove the previous services first.
Delete Windows Services
Open a powershell window as an administrator and run the following commands:
sc.exe stop DimeSchedulerServiceBus
sc.exe delete DimeSchedulerServiceBus
sc.exe stop DimeSchedulerBackOffice
sc.exe delete DimeSchedulerBackOffice
This will remove the services. Don't worry, the installer will reinstall it later.
There's a few ways to remove the programs. Arguably the easiest way to achieve this is through PowerShell:
get-package *Dime.Scheduler* | uninstall-package
This might prompt some confirmation windows to proceed with the uninstallation. Click yes and let the command do its job.
Alternatively, you can go to the 'Program and Features' Windows settings window and remove the Dime.Scheduler services. Don't worry if you had already installed the new Office 365 - based Exchange connector, it won't appear in the list - this already uses the new hosting model.
To validate, check whether the Dime.Scheduler directories in the Program Files folder are empty. If you had already installed the new Office 365 - based Exchange connector, the directory doesn't need to be empty as it already uses the new hosting model.
It's best to reboot the server at this point to prevent any further issues in the remainder of the upgrade process.
After this step, you may proceed with the general upgrade guide.