Hi Halil,
I've done as you said. The UserId shown from AbpSession is '1' and TenantId is null. As you know, '1' is the admin UserId.
Repeated the same after including the AbpAuthorize attribute and after giving a user-wise permission in AbpPermissions table. Now also getting the same result.
Oh.. I'm really Sorry.. I've typed it mistakenly. The error is not at the point of creating the new tenant, its happening at the point of Creating a Default Institute for the new Tenant (in TenantAppService).
Another interesting fact is, everything is working perfectly when i remove the [AbpAuthorize(PermissionNames.Pages_Institution)] from InstitutionAppService
But, I've given permission for the same to the admin user role in the table 'AbpPermissions' A screenshot of the same is attached.
PermissionNames
Public const string Pages_Institution = "Pages.Institution";