I'm trying to create a new Communication Site in my tenant.
I see option for create this site, I compiled fields and it says is ok to proceed.
But, when I click on finish, browser sent message to exit or remain in page and in every case, it broke page with "Unable to reach https://_layouts page"
I searched for call in F12 and found this:
POST to https://[tenant].sharepoint.com/_api/sitepages/publishingsite/create
code > -2147024891, System.UnauthorizedAccessExceptionmessage >Access Denied, etc etc
My account is tenant administrator.
I've checked licence and it's all ok.
Tryed with all browser (edge, ie11, chrome).
The problem was access denied on root site collection of tenant..
Mysteriously, even if I navigate without problems to https://[tenant].sharepoint.com/_layouts/sharepoint.aspx, call to https://[tenant].sharepoint.com/_api/sitepages/etc.. was forbidden.
If I navigate to https://[tenant].sharepoint.com/ my account receives access denied.
So, I give Site Collection Administrator rights to my user (with SharePoint Administration) and my new Communication Site is here!