Registration Wizard Error: Error issuing app only token

Problem

Registration Wizard fails at the Administrative OAuth Token step and returns the following error:Open AuthorizationError issuing app only token.

There are no further error messages found in the host server logs. Running a ProcMon (https://learn.microsoft.com/en-us/sysinternals/downloads/procmon) trace while replicating the issue shows an ACCESS DENIED on the following paths:- C:\Users\{K2 Service Account}\AppData\Local\Temp- C:\ProgramData\Microsoft\Crypto\RSA\MachineKeys

Solution

Ensure that both K2 Service Account and K2 Application Pool Account have at least read, write and delete permissions on those folders.