I downloaded the latest esd-decrypter-wimlib-37 back then and got the message below. So esd-decrypter-wimlib-8 is the latest for Windows 8.1 ESD's.
Not sure what you mean. Can't use v37 (or v18) to convert the latest Windows 8.1 IR5 ESD to an ISO file as per text in decrypt.cmd. So downloaded v8 from the link above provided by abbodi, which doesn't have the warning text. In any case, the info will help anyone else trying to convert a Windows 8.1 ESD to an ISO file.
You are changing the wrong key, the correct is Package_for_KB2976978~31bf3856ad364e35~amd64~~6.3.2.1 or start cmd with NSudo as TrustedInstaller and execute: Code: reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Component Based Servicing\Packages\Package_for_KB2976978~31bf3856ad364e35~amd64~~6.3.2.1\Owners" /v Package_for_KB2976978~31bf3856ad364e35~amd64~~6.3.2.1 /t REG_DWORD /d 0x20070 /f dism /Online /NoRestart /Remove-Package /PackageName:Package_for_KB2976978~31bf3856ad364e35~amd64~~6.3.2.1