Import item to content library fails with 'Unable to finish importing'

Products

• VMware vCenter Server

Issue/Introduction

Import item to the content library fails intermittently with error "A general system error occurred: The import of library item ######-###-###-##-###### has failed. Reason: Unable to finish importing." 

In /var/log/vmware/content-library logs, following behavior is observed:

Transfer session gets created:

INFO | ... | TransferSessionImpl | Created new transfer session ##############
DEBUG | ... | CreateSessionActivity | Created transfer session urn:transfer:################## for update session #######-####-####-####-######### to library item test_iso (ID: #####-##-####-##-#############) in library Publisher
...
INFO | ... | HttpServerEndpointImpl | Session ##############: Validated PUT request for /cls/data/##############/test.iso, (0 / ? bytes transferred)
DEBUG | ... | HttpServerEndpointImpl | Served endpoint for ##############/test.iso: Ready

The 'Ready' event repeats every 6-7 s and item never gets dequeued in the interval of 2 minutes:

DEBUG | ... | HttpServerEndpointImpl | Served endpoint for ##############/test.iso: Ready

Transfer session is released 2 minutes later:

DEBUG | ... | TransferSessionCleanerImpl | queueing release of transfer session urn:transfer:##############
INFO | ... | TransferSessionImpl | Releasing transfer session ##############
...
INFO | null | transferService-pool-7-thread-2393 | TransferItemImpl | Transfer of item test.iso in session ############## has been attempted 1 times.
DEBUG | ... | TransferItemImpl | Session ##############: Transfer item ##############/test.iso has been released, nothing to do

Environment

VMware vCenter Server 8.x

Cause

This occurs because active Sync Library operations are consuming all available transfer sessions.

For example, if Maximum number of concurrent transfers is set to 2 and Sync Library is using both slots, any newly triggered import will remain on hold until one of those sessions is released.

Resolution

1. Adjust the sync window and perform imports outside of it to prevent transfer session conflicts between sync and import operations.

2. Increase the concurrent transfer session count 

(Both of the above settings are highlighted below:)