Ugh! You've just tried for the 10th time to update a VS 2017 offline installer, and it's failed with
Launched extracted application exiting with result code: 0x57
in your temp\dd_mu_visual_studio_professional_2017_x86_x64_*_decompression_log.txt and
Unable to parse the json file since it not exists: 0
in your temp\dd_bootstrapper_*.log . ("Not exists???")
What's happening? Probably you ran the installer fron the layout target folder, not the (identical) installer that you downloaded from MS, but put in some other folder. Run the latter with the same arguments, and your offline installer update is likely to get past at least this error.
Also, do NOT use the "update" command-line argument; that is, don't do this:
mu_visual_studio_*.exe update --layout c:\<layout_target_folder>
mu_visual_studio_*.exe --layout c:\<layout_target_folder>
I still do not understand why MS replaced simple, reliable .iso file downloads with the unholy mess that builds their offline installer. The new approach is buggier, slower, more difficult to use, more difficult to diagnose, less secure in that it requires you to give network access to a mess of new programs, and more difficult to control.
Please, MS, bring back .iso downloads. And sign them with GPG while you're at it.