can create sites but not able to see them

Hello all,
I’ve just installed a brand new multisite with subdirectories; I added the said codes where they were supposed to go and everything seemed to go well until I created a dummy subdirectory called “prova”.

The trouble is that I can’t access to it. It gives me a “error establishing database connection”.
Also, when I try to access the dashboard for “/prova”, I get redirected to the network dashboard.

What should I do?

The host is GoDaddy
the main website is alessandraleone.it
and the dummy should be alessandraleone.it/prova