Sitecore App Center returns SOAP Exception when Sitecore Email Campaign Manager when calling RegisterSenderEmail

When sending though Sitecore Email Campaign Manager you might experience the following exception:

Exception: System.Web.Services.Protocols.SoapException
Message: Server was unable to process request. —> Object reference not set to an instance of an object.
Source: System.Web.Services
at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
at Sitecore.Modules.EmailCampaign.SitecoreApps20.EmailDelivery.RegisterSenderEmail(Credentials credentials, String email)
at Sitecore.Modules.EmailCampaign.Core.MessageTransfer.AppCenter.RegisterSenderEmail(String email)
at Sitecore.Modules.EmailCampaign.SendingManager..ctor(MessageItem message, Boolean isService)
at Sitecore.Modules.EmailCampaign.UI.Dialogs.TestSendWizard.RunQuickTest()
at Sitecore.Modules.EmailCampaign.UI.Dialogs.TestSendWizard.ActivePageChanging(String cur, String& next)
at Sitecore.Web.UI.Pages.WizardForm.set_Active(String value)
at Sitecore.Web.UI.Pages.WizardForm.Next()
at Sitecore.Web.UI.Pages.WizardForm.OnNext(Object sender, EventArgs formEventArgs)
at Sitecore.Web.UI.HtmlControls.Button.DoClick(Message message)

Problem: Some versions of the Sitecore Email Campaign Manager will not check if the Email Delivery App has been purchased in the Sitecore App Center. This exception occurs if out have not yet signed up for the Email Delivery.

Solution: The issue should be fixed simply by purchasing the Email Delivery App in the Sitecore App Center.

Sitecore App Center: No access to license alert dialog

When entering or logging in to the Sitecore App Center, then following alert message might be displayed:

EN: “The credentials that you have used to login to the Sitecore App Center, does not have access to the license used on this server.”
DK: “De legitimationsoplysninger, du har benyttet til at logge på Sitecore App Center, har ikke adgang til den licens, der bruges på denne server.”
GE: “Mit den Benutzerdaten, die Sie zur Anmeldung beim Sitecore App Center, eingegeben haben, ist kein Zugang zur auf diesem Server verwendeten Lizenz möglich.”
JP: “Sitecore App Center にログインするために使用した資格証明には、このサーバーで使用するライセンスへのアクセス権がありません。”

PROBLEM: Your Sitecore Single Sign Credentials is associated with an Account at Sitecore. The Sitecore Server that you that you logged in to has a license file. This license file is also associated with a Account at Sitecore. This alert is displayed when you log in with Credentials where the associated Account does not match the associated Account of the license file on the Sitecore Server. This typically happens for partners when are working on customer solutions.

SOLUTION: Use a logging that is associated with the account of the license or change the license file of the solution to a license of your account. NOTE: The website will have to be reset after changing the license file.

Sitecore App Center, childs play video