Today I went through and upgraded our Veeam Backup and Replication Platform from v7 to v8. Overall the in place upgrade was painless, quick and efficient…however I came across an error when going through test runs of existing jobs that I had not seen in previous Veeam B&R Versions.


So after what looks like a successful backup the Error: Completion timeout occurred is shown and the job finishes with errors. I Tweeted the solution soon afterwards, but thought it was worth a quick follow-up post:

Veeam KB1976 describes the cause of the error as:

Unless the preferred network is specified, by default Veeam will attempt to establish a connection with each NIC on the target host and then automatically determine which one it should use. When there are multiple NICs and connectivity is only possible to some of them, sometimes the agent will retry establishing connections on the other NICs until it times out.

In my case the Backup Server also houses a Repository which is configured to point at an iSCSI Target LUN served off a DELL MD3200i. The basic configuration of the iSCSI Targets has two vNICs that connect and cross over to each Storage Controller of the MD along with the Management/Backup vNIC that used to talk to the vCenter/ESXi Hosts and Veeam Proxy and Repo Servers.


As described in the KB, what was happening was that Veeam 8 Agent was trying to talk through the iSCSI vNICs which are not routed…hence leading to the timeout error. To fix this (as described here) you need to specify a priority network for data transfer.

Select Network Traffic from the Main Menu in the Veeam B&R Console then Click on Networks and check Prefer the Following networks for backup and replication traffic and then Add in the network and subnet as shown below.


I reran the job without issues and the problem was solved. The Preferred Networks can be useful if you have separate backups networks and want to route VM data traffic over that instead of a production network…not relevant in my case but a decent design option at your disposal when considering Veeam 8 Backup Networks.