Just upgraded to Veeam B&R 9.5u4a yesterday and the backups last night have all failed. It also seems to have stopped after the first three failures, even though there are six VMs in this backup job.
3/07/2019 11:15:47 p.m. :: Processing [i]Computer_Name[/i] Error: Failed to open VDDK disk [[SSD2] [i]Computer_Name[/i]/[i]Computer_Name[/i].vmdk] ( is read-only mode - [true] )
Logon attempt with parameters [VC/ESX: [10.0.50.20];Port: 902;Login: [root];VMX Spec: [moref=18];Snapshot mor: [18-snapshot-3614];Transports: [nbd];Read Only: [true]] failed because of the following errors:
Failed to open disk for read.
Failed to upload disk.
Agent failed to process method {DataTransfer.SyncDisk}.
3/07/2019 11:15:52 p.m. :: Processing [i]Computer_Name2[/i] Error: Failed to open VDDK disk [[SSD3] [i]Computer_Name2[/i]/[i]Computer_Name2[/i].vmdk] ( is read-only mode - [true] )
Logon attempt with parameters [VC/ESX: [10.0.50.20];Port: 902;Login: [root];VMX Spec: [moref=13];Snapshot mor: [13-snapshot-4067];Transports: [nbd];Read Only: [true]] failed because of the following errors:
Failed to open disk for read.
Failed to upload disk.
Agent failed to process method {DataTransfer.SyncDisk}.
3/07/2019 11:17:57 p.m. :: Processing [i]Computer_Name3[/i] Error: Failed to open VDDK disk [[SSD1] [i]Computer_Name3[/i]/[i]Computer_Name3[/i].vmdk] ( is read-only mode - [true] )
Logon attempt with parameters [VC/ESX: [10.0.50.20];Port: 902;Login: [root];VMX Spec: [moref=20];Snapshot mor: [20-snapshot-427];Transports: [nbd];Read Only: [true]] failed because of the following errors:
Failed to open disk for read.
Failed to upload disk.
Agent failed to process method {DataTransfer.SyncDisk}.
Veeam Support say that it is caused by one of the VMWare hosts being ESXi 5.1.0. That explains why only some VMs failed, the other VMs are on ESXi 5.5.0 hosts.
Yes, we have it for U4b as well. Feel free to obtain it from our support team. The KB will be updated a bit later once we have a sufficient amount of feedback.
Update: KB2875 has been updated with the fix for U4b.