When attempting to perform a conversion the workflow fails with error: A file I/O error occurred while accessing

Products

• VMware vCenter Server
• Converter

Issue/Introduction

• When attempting to perform a conversion the workflow fails with error:
  
  A file I/O error occurred while accessing "
  
  
  
  
  
  
  
  
• Logs show the following errors:
  
  vmware-converter-worker.log 
yyyy-mm-ddThh:mm:ss.zzz warning vmware-converter-worker[33888] [Originator@6876 sub=Default] [,0] [NFC ERROR]Nfc_BindAndEstablishAuthdCnx3: Failed to create a connection with server <Destination_ESXi_Host>: Failed to connect to server <Destination_ESXi_Host>:902 
yyyy-mm-ddThh:mm:ss.zzz info vmware-converter-worker[33888] [Originator@6876 sub=Default] Sysimgbase_DiskLib_OpenWithPassPhrase failed with 'NBD_ERR_NETWORK_CONNECT' (error code:2338) 
yyyy-mm-ddThh:mm:ss.zzz warning vmware-converter-worker[33888] [Originator@6876 sub=Default] [,0] [NFC ERROR]NfcNewAuthdConnectionEx: Failed to connect: Failed to connect to server <Destination_ESXi_Host>:902
yyyy-mm-ddThh:mm:ss.zzz warning vmware-converter-worker[33888] [Originator@6876 sub=Default] [,0] [NFC ERROR]NfcNewAuthdConnectionEx: Failed to connect to peer. Error: Failed to connect to server <Destination_ESXi_Host>:902
yyyy-mm-ddThh:mm:ss.zzz warning vmware-converter-worker[33888] [Originator@6876 sub=Default] [,0] [NFC ERROR]NfcEstablishAuthCnxToServer: Failed to create new AuthD connection: Failed to connect to server <Destination_ESXi_Host>:902
..
yyyy-mm-ddThh:mm:ss.zzz error vmware-converter-worker[70384] [Originator@6876 sub=Default] [BaseDiskSetComputer::AnalyzeErrorAndThrow] Error occurred when opening disk set, MNTAPI_ERROR = 37409 MNTAPI
 errorType = 1, errorCode = 2338
yyyy-mm-ddThh:mm:ss.zzz error vmware-converter-worker[70384] [Originator@6876 sub=Default] AnalyzeErrorAndThrow(): Opening virtual disk failed with error 'NBD_ERR_NETWORK_CONNECT' (error code:2338)
2025-12-09T13:17:25.592+02:00 error vmware-converter-worker[70384] [Originator@6876 sub=Default] TargetVmManagerImpl::CreateVM: Failed to retrieve the storage mapping with error Fault cause: converter.fault
.FileIOFault

Environment

VMware vCenter Converter Standalone

Cause

The above error suggests a communication problem between the Converter server and the ESXi hosts on port 902.

That could be related to various reasons including:

• Physical network misconfiguration
  
  
• Firewall / SSL inspection / Antivirus tool blocking the traffic on TCP port 902

Resolution

Engage your Network Team to investigate the traffic between the Converter server, the ESXi host and the Source Machine on port TCP 902

Additional Information

vCenter Converter Standalone - TCP/IP and UDP Port Requirements for Conversion