.PL Yes, the account used is indeed the admin of the machine.
Bart: It's a migration from 2012 to 2015.
I did a 100% manual and antivirus-free installation based on an administrative image on Friday morning. No problem encountered.
On the same machine and under the same conditions, except that I launched the " startswinstall.exe " file from a batch file Call startswinstall.exe The installation did not complete.
The problem has not really been solved but as many elements have changed, such as the deployment mode which was not done at the start of the machine but once the user session was opened, for example.