Job fails right away with error "Checking free space on source datastore. Object reference not set to an instance of an object."
In the log files you can see:
[timestamp] Info Task operation: 'Checking free space on source datastore'
[timestamp] Info [AP] Disposing client from thread 1
[timestamp] Info [AP] Sending quit signal for client, host "esxhost"
[timestamp] Info [AP] (Server) state: closed
[timestamp] Info [AP] (Client) state: closed
[timestamp] Info [AP] Stopping local agent process, pid 5936, role Client
[timestamp] Info [Soap] Connection 'vc:443:domain\administrator:False::0:1' is disposing.
[timestamp] Info [Ssh] Connection 'esxhost:22:root:False:False:1' is disposing.
[timestamp] Info [AP] Disposing client from thread 1
[timestamp] Info [AP] Sending quit signal for client, host "esxhost"
[timestamp] Info [AP] (Server) state: closed
[timestamp] Info [AP] (Client) state: closed
[timestamp] Info Starting perlSoap protocol to "esxhost"
[timestamp] Info Installing perlsoap library to /tmp/veeb8f283e5-2eb1-4ef6-8403-c5843e8aaf65
[timestamp] Info Reading "veeam_soap.tar" from directory "C:\Program Files\Veeam\Backup and Replication\"
[timestamp] Info Answer to installation: :
[timestamp] Info Executing firewall command "ClosePortOut", port 2500
[timestamp] Info [Soap] Connection 'vc:443:domain\administrator:False::0:1' is disposing.
[timestamp] Info Unlocking storage(s), lockId: '62ebbc13-f147-4502-a0c9-745c5af4e0fb'
[timestamp] Error Object reference not set to an instance of an object. in Veeam.Backup.Core.CFreeSpaceChecker.CheckFreeSpaceOnSourceDatasore(CBackupTaskSession taskSess, Datastore datastore)
[timestamp] Error in Veeam.Backup.Core.CVddkSource.Backup(IReceiver receiver)
[timestamp] Error in Veeam.Backup.Core.CBackupJobPerformer.ExecuteTask(IVmBackupTask task, ITarget target, CBackupTaskSession taskSess)
[timestamp] Error in Veeam.Backup.Core.CBackupJobPerformer.ExecuteTask(IBackupTask task, ITarget target)
You have a workingDir parameter in the vmx file of the VM