SoapUI calling AIF error: Malformed UTF-8 character: 0xfc 0x6c 0x74 0x6

When you import a AX AIF WSDL from SoapUI you might face an error telling you that SoapUI has stumbled accross a malformed UTF-8 character. Especially when you are in a non english environment.

Error loading [https://our.externalserviceurl.com/MicrosoftDynamicsAXAif60/OURsmallHTTPService/xppservice.svc?wsdl]: org.apache.xmlbeans.XmlException: java.io.CharConversionException: Malformed UTF-8 character: 0xfc 0x6c 0x74 0x6

Looking at the WSDL and all the imports there is no character which is not UTF-8 conform. After checking the communication between the servers I found out that the IIS was responding to the WSDL request with a 401 page. This response was in german and contained german characters ("ü").

In my case it was required to set the http authorization to NTLM to enable SoapUI to authorize correctly through http. So whenever you get this malformed UTF-8 error check the communication.