I was getting the same problem trying to boot from an ISO which I've booted several times before. I recently upgraded VMWare Host to 6.7 and there my problem started. I had tried the solutions listed in the previous reply with no avail. But the solution was turning on "Secure Boot" in the settings of the VM under VM Options > Boot Options > Secure Boot.
Once I turned this option on the ISO booted without any further issues.
Here is the link that led me to the solution:
https://blogs.vmware.com/vsphere/2019/09/microsoft-windows-server-2019-stig-vmware-vsphere.html
Good Luck
