Ive not installed any updates.
I've installed EPiServer Commerce 9.16 from nuGet in Visual Studio 2015.
Just to make sure, you did install two sites: One with Episerver.Commerce and one with Episerver.CommerceManager?
I did install both packages Episerver.Commerce and Episerver.CommerceManager from NuGet, in version 9.16.0
That's not how it works. You should have two site. You can create a site from Episerver Visual Studio extension, then install Episerver.Commerce to it. Create another empty ASP.NET site in same solution then install Episerver.CommerceManager to it.
I've just installed the last EPiServer CMS 9.9.1, and test it with no problem. Today I've installed EPiServer Commerce 9.16 but after this operation I cannot login into backend.
When I link to http://mysite.me/episerver EPiSever return an Access Denied error:
"Your account does not have rights to access this feature of the commerce manager. Please contact your system administrator for more information."
I've checked my Web.config and both "membership" and "roleManager" are configured with "WindowsMembershipProvider" and "WindowsRoleProvider"
Checking online it seems like a bug already fixed in EPiServer Commerce 7.5.