When you try to use the BizTalk Server adapter for Windows SharePoint Services to access an instance of SharePoint Online (SPO), you may receive the following error message:
A message sent to adapter" Windows SharePoint Services" on send port "PortName" with URI "wsss://o365-path" is suspended. Error details: [System.NullReferenceException] Object reference not set to an instance of an object.
For information about the service packs and cumulative update list for BizTalk Server, click the following article number to view the article in the Microsoft Knowledge Base:
2555976 Service Pack and cumulative update list for BizTalk Server
For more information about BizTalk Server hotfixes, click the following article number to view the article in the Microsoft Knowledge Base:
2003907 Information about BizTalk hotfixes and Cumulative Update support