Symptoms
The MSMQ Adapter for BizTalk is returning an IndexOutOfRangeException when using a send port without Reply to Queue and Reply To Queue Manager properties present.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Resolution
This issue is fixed in the following cumulative update for Host Integration Server:
Cumulative Update 1 for Host Integration Server 2020
References
Learn about the terminology that Microsoft uses to describe software updates.