One prerequisite for migrating from EPiServer 4 to 5 is that the site in question is upgraded to version 4.62B. During this upgrade I came across the following error:

Running Assembly installer for EPiServer.SchedulerSvc.exe:"Cannot install files: The installation failed, and the rollback has been performed. [The name is already in use as either a service name or a service display name]"

Because of this conflict with the CMS5-scheduler the upgrade halted.

The solution is to temporarily remove the EPiServer 5 scheduler (it can be re-installed using the episerver manager/install manager, or from command-line).
To remove the scheduler service do one of the following:

  1. run InstallUtil.exe  /u ” C:\Program Files\EPiServer.Scheduler5(eller 4)\ EPiServer.SchedulerSvc.exe, or
  2. Delete the SchedulerService from registry (found under HKEY_LOCAL_MACHINE, SYSTEM, CurrentControlSet, Services) - PS! Requires ree-boot

In my case the latter did the trick, and the upgrade completed as expected.
Next step now is running the migration tool...