Sync Library Item task for Subscribed Content Library fails with error "A general system error occurred:Error transferring file...Reason: Error while uploading to datastore"

Products

• VMware vCenter Server

Issue/Introduction

When performing a Sync Task for Subscribed Content Library, following error appears on the UI : 

A general system error occurred:Error transferring file Template_Name.vmdk to ds:///vmfs/volumes/45######-#######-####-########79/Content_Library_Folder/Template_Name.vmdk?serverId=56#####-####-####-#####45. Reason: Error while uploading to datastore (ds:///vmfs/volumes/45######-#######-####-########79/Content_Library_Folder/Template_Name.vmdk?serverId=56#####-####-####-#####45): Connection reset

Under the content library service logs on vCenter Server, following error is reported. 
Log location - /var/log/vmware/content-library/cls.log : 

YYYY-MM-DD HH:MM:SS  | INFO     | abc####-#####-auto-####-h5 | transferService-pool-7-thread-1624 | TransferEndpointImpl           | Session 4a####################fg: Transfer failed! item: Template_Name.vmdk; bytes transferred: 5114275743; total bytes: 22375563264; error: Transfer cancelled
YYYY-MM-DD HH:MM:SS  | DEBUG    | abc####-#####-auto-####-h5 | transferService-pool-7-thread-1624 | TransferInputStream            | Session 4a####################fg, Item Template_Name.vmdk: Closed the input stream successfully
YYYY-MM-DD HH:MM:SS  | INFO     | abc####-#####-auto-####-h5 | transferService-pool-7-thread-1624 | TransferEndpointImpl           | Session 4a####################fg, Item Template_Name.vmdk: Transfer done for endpoint NfcEndpointImpl, size = 5114259359
YYYY-MM-DD HH:MM:SS  | INFO     | abc####-#####-auto-####-h5 | transferService-pool-7-thread-1624 | TransferEndpointImpl           | Session 4a####################fg: Transfer failed! item: Template_Name.vmdk; bytes transferred: 5114259359; total bytes: 22375563264; error: Error while uploading to datastore (ds:///vmfs/volumes/45######-#######-####-########79/Content_Library_Folder/Template_Name.vmdk?serverId=56#####-####-####-#####45): Connection reset


Environment

VMware vCenter Server 

Cause

The above log entries confirm that the transfer consistently fails when approximately 5 GB of data has been uploaded. This behavior is observed during every sync attempt, indicating a recurring network connection drop or timeout occurring around the same data threshold.

NOTE : Bytes transferred can differ from environment to environment. 

Resolution

Engage the internal networking team to investigate the root cause of the consistent upload failure, which occurs after transferring approximately the same amount of data each time.

Additional Information

This behavior has been observed in environments with intermediate firewalls or deep packet inspection devices enforcing thresholds on session time or payload size