HCI NDE fails with "The vcenter server is not valid" error when trying to add storage or compute node

Applies to

• NetApp HCI 1.3 - 1.5
• HCI Storage Element OS 
• HCI Deployment Engine/Monitoring Agent

Issue

When expanding a NetApp HCI system with NDE and trying to add one compute node to the existing cluster, you may experience a failure with the "The vCenter Server is not valid" error being generated during the phase when compute nodes are added to the initial ESXi cluster.

The logs report the following: 
  
2019-01-08T15:11:33.758263Z | 24027 | 1086178002 | MainProcess-MainThread | management:198 | DEBUG | current_ver=6.5.0 minimum 6.0 version=6.0.0.5183549 minimum 6.5 version=6.5.0.5973321 
2019-01-08T15:11:34.097206Z | 24027 | 1086178340 | MainProcess-MainThread | app:1560 | ERROR | Exception on /api/2/en_US/nde/auth/vcenter-connection [POST] 
Traceback (most recent call last): 
  File "site-packages/flask/app.py", line 1612, in full_dispatch_request 
  File "site-packages/flask/app.py", line 1598, in dispatch_request 
  File "site-packages/flask_restplus/api.py", line 313, in wrapper 
  File "site-packages/flask/views.py", line 84, in view 
  File "site-packages/flask_restplus/resource.py", line 44, in dispatch_request 
  File "sfprime/scale/scale_authorization.py", line 296, in decorator 
  File "sfprime/nde/nde_api.py", line 417, in post 
  File "sfprime/vmware/management.py", line 172, in verify_license 
  File "sfprime/vmware/management.py", line 1169, in verify_vcenter_license 
  File "sfprime/vmware/management.py", line 1263, in verify_active 
  File "sfprime/vmware/management.py", line 1232, in expiration 
  File "sfprime/vmware/management.py", line 1253, in __getitem__ 
KeyError: 'expirationDate not found' 

Concurrently, vCenter will show the license as present in the Licenses tab but with "Never" in the "Expiration" column.