Encountered illegal extension attribute ‘nillable’. Extension attributes must be in a namespace other than WSDL’s

This happened to me when I was trying to add a new SOAP project to SOAPUI. If you don’t already know, SOAPUI is a fantastic tool for use with SOAP web services. Over many years I have never found anything better. Having said that, I don’t use it that much, but when I do it’s irreplaceable.

The particular SOAP service I was trying to connect to is one I have connected too in the past so I knew it was unlikely that the issue was with the WSDL itself and even if there was it was from a third party. I also remembered from the dim dark past that I had come across this issue before, unfortunately for me I didn’t recall the solution I had previously used but had a feeling it was fairly straightforward.

Here is what worked for me. The first step was to create a copy of the wsdl as a file. To do that I just browse to the location of the wsdl e.g. https://myWebService/MyService.asmx?wsdl using my web browser. I then use the view source option and copy and paste into a file which I give the .wsdl extension.

To fix the actual issue without adversely affecting the wsdl we need to add a new namespace. I added this namespace as xsi wasn’t already used.


This meant that I had to put all my nullable attributes into the xsi namespace by simply replacing nillable with xsi:nillable. This wsdl can then be added to SOAPUI and it worked as normal.

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Steve Ellwood

Senior Integrations Officer at Doncaster Council Any views expressed are entirely my own.