HCX MON network extensions fails with the error: "Failed to configure # vnics for Mobility Optimized Networking"

Products

• VMware HCX

Issue/Introduction

• You are extending a network that was previously extended and unextended. 
• Tasks are progressing up to %, failing, and rolling back. 
• You can extend the network without MON (Mobility Optimized Networking).
• The following error is observed in /common/logs/admin/app.log, when MON is enabled:
  

  [NetworkStretchService_SvcThread-2297, j: c3850ec8, s: ########, , TxId: ########-####-####-####-############] ERROR c.v.v.h.n.i.AbstractJobInt- NetworkStretchJobs workflow BridgeNetworksJobInt failed. Error: Failed to configure 1 vnics for Mobility Optimized Networking. Successfully configured 0 vnics. Failed vms: [VM Name]
  [NetworkStretchService_SvcThread-2297, j: c3850ec8, s: ########, , TxId: ########-####-####-####-############] WARN  c.v.v.h.n.i.AbstractJobInt- Exception in NetworkStretchJobs:ExtendNetworkWorkflowInt. Reason : Failed to configure 1 vnics for Mobility Optimized Networking. Successfully configured 0 vnics. Failed vms: [VM Name]
  [NetworkStretchService_SvcThread-2297, j: c3850ec8, s: ########, , TxId: ########-####-####-####-############] ERROR c.v.v.h.n.i.NetworkStretchJobInt- Error encountered in Network Stretch job java.lang.RuntimeException: Failed to configure 1 vnics for Mobility Optimized Networking. Successfully configured 0 vnics. Failed vms: [VM Name]
  

Environment

VMware HCX

Cause

Failed task related to the VM that was highlighted in the logs. 

Resolution

• Edit the VM in the Destination vCenter 
• Change the attched portgroup temporarily.
• Re-extend the network/ Enable MON.