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.
Cumulative update information
This problem was fixed in the following cumulative update for BizTalk Server:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
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