We did faced the same issue when setting up the Qlik Sense Server
As mentioned by Levi Turnor use command propmpt -> go to the directory where the "Qlik_Sense_setup.exe" exists and Run Qlik_Sense_setup.exe -skipvalidation Qlik_Sense_setup.exe skipvalidation=1
This should solve the "Service User Validation Failed" error. Thanks....
Can u please elaborate your solution...
I am trying your solution but its not working..
We navigated to the path where qlik sense setup is there..
then we run the set up reaching to the service credentials page..
n then we copied the skip validation code as Qlik_Sense_setup.exe skipvalidation=1
But its not working..
Please help me with the solution...