Sorry, but the quickstart package is Joomla 3.8.1 and we never had update problems.
BTW which local Server is in use and which PHP version?

PS: XAMPP is bad, because you cant switch easy the PHP vesions.
We recommend the UWAMPP, its a french developer Apache
www.uwamp.com/fr/

We have updated the Gusto quickstart to Joomla 3.9 withpout any problems.
You can download the new package from our server right now.

Thank you very much, installation Ok, database repaired (many errors), nothing in Discover, but, as you can see in attached file, only 3 components in list.
Any Idea ?
My local web server is AMPPS on Mac, Version PHP : 7.1.8 - My`S£QL 5.6.37

Its a Joomla Bug
github.com/joomla/joomla-cms/blob/stagin...3.7.0-2017-01-17.sql

BTW we have fixed the quickstart package again. Now all extensions are listed.

Hello, today Joomla 3.9.1 update failed, invalid login message, problem is not solved!
I have two server on local, same error on both.
I have published the website online on my dedicated server, and the problem is the same, update not working.
This is very serious for me, you will understand that I can not use this theme if I can not update Joomla thereafter, which represents 3 days of lost work at this time, plus time waiting for your intervention.
You really have to find the solution to this bug, which in my opinion must come from a modified core file or one of your extensions that prevents this update.
I can give you admin access to this website now, tell me how please.

I have found the problem : Google Chrome !!!
Incredible, with others browser update works,
Never again will I use this software!
Sorry for all of this but it was still highly unlikely that it came from that, no one had thought of it.