Creating new site is not possible :(

Are you using WordPress multisite?

Does it work if you temporarily deactivate all plugins and activate the default Twenty Fifteen theme?

Yes I’m using multisite. I don’t think the problem be plugins and themes. It’s about creating databases. There are other forums already talking about this.
Read this:
https://www.ads-software.com/support/topic/can-not-add-new-site-wpmu?replies=46

Sorry, I missed that. Thought I was in another forum. Still, my questions remain the same.

I have edited my last reply. Could you please check it again. Thanks.

I don’t think the problem be plugins and themes. It’s about creating databases. There are other forums already talking about this.
Read this:
https://www.ads-software.com/support/topic/can-not-add-new-site-wpmu?replies=46