A few days ago, before implementing user management using the Azure Active Directory graphing API (not Microsoft Graph) in our web application for Azure AD B2C users, I managed to log in to the Azure Portal, find the Azure Active Directory B2C resource, click on it and successfully authenticate in it to edit policies, view a list of users, etc.
(Click on the tenant in the screenshot that was used to work!)
Now, when I click on it, the screen blinks about 10 times, trying to record my user in the tenant. But then the following error is returned:

In addition, when I try to log into a web application with the same user, I get the following error message:
. . , , .
, Azure AD B2C? AAD Graph Client?
UPDATE
, Azure AD Graph Client, , , - AAD B2C-.
, , Azure AD Graph Client, , / "":
x AAD B2C , , y GUID .
HTTP PATCH to https:
Body: {
"extension_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx_Organization":"Microsoft"
}
? AAD B2C , ?
UPDATE
, , AAD B2C: https://blogs.msdn.microsoft.com/azureadb2c/2016/09/09/known-issue-b2c-app-mgmt/
? ( - , , , , , )