I can't reproduce this. After having clicked the button to remove the installation folder, I see:

That means in my case the button has the right text, while the button in your screenshot still has text from before removal.

Ok, that text in the yellow box "PLEASE REMEMBER ..." is silly, but that is an old thing I think, as far as I remember it was always like this.

Could you test again with current staging?

I think he wants the yellow box to disappear upon successful installation.

Successful installation folder removal you mean, I hope.

On second thought, maybe remove the text only in the yellow box after successful removal.

Yes, that could be easier and sufficient.

Just to make sure I wasn't smoking something I repeated the install, using latest clone.
pre-click...

post-click

additional clicks not available.

+1 on removing the "PLEASE REMEMBER..." post click as its no longer necessary if the button click has successfully removed the folder

I also can't reproduce this:After clicking the button I see:

@pau1a what LAMP stack are you using? Recently I had an issue with WSL Ubuntu not updating extensions properly but "Neard" ( wamp clone ) behaving perfectly.

@N6REJ The test I did earlier was on an Ubuntu 16.04.6 LTS box running PHP 7.2.18-1 , Apache/2.4.18 and MYSQL 5.7.26.
I used the Joomla! 3.9.11-dev Development staging build

the only "major" diff between our builds ( besides platform ) is I did it on ubuntu 18.10(?) and mariadb10.xxx
makes me wonder.....
in Neard I'm getting session error if I switch from mysql 5.7 to maria10

let me try another install using neard and see if same error pops

any php errors?

not that I saw... just tested and working fine with latest pull & mysql 5.7 Going to try maria next.

nope, won't install in mariadb 10.xxxx
Error
Could not connect to the database. Connector returned number: Could not connect to MySQL server.

@pau1a just tried with mariadb 5.5.60 and had same failure.

@pau1a ok, more info.. mariadb was on port 3307 and mysql was on 3306, there is no option for changing ports nor selecting mariadb in J!. Changing maria to 3306 solved the issue in all forms & versions.
so, it seems this is a wsl specific issue.

Interesting.. I didn't know you were running an external DB.

http://neard.io it's a variant of wamp
wsl = Windows Subsystem for Linux
I was trying both as wsl is MUCH faster and lighter then wamp or any vm(ish) method

@N6REJ OK to close?

@Quy yeah, who knows what kind of flakiness wsl is doing to the kernel.