Triage: Alternating "Server Refused Connection" Failures on Disk 0 During Incremental Sync (50% Failure Rate) #1390
Description
What steps did you take and what happened?
Created a migration for a VM with 2 disks, 2 disks initial copy succeeded without any issues. Seeing the following behaviour when periodic sync is enabled:
Every time a new snapshot is created, the first attempt to copy Disk 0 fails immediately with a "Server refused connection" error. The process retries exactly one hour later using the same snapshot, and that retry always succeeds. This pattern repeats indefinitely.
[2026-01-14T08:52:13Z] | snapshot-166125 | FAILED
[2026-01-14T09:52:29Z] | snapshot-166125 | SUCCESS (1m38.620711896s)
[2026-01-14T10:52:37Z] | snapshot-166126 | FAILED
[2026-01-14T11:51:11Z] | snapshot-166126 | SUCCESS (1m26.352883109s)
[2026-01-14T12:51:13Z] | snapshot-166131 | FAILED
[2026-01-14T13:49:54Z] | snapshot-166131 | SUCCESS (1m19.402282238s)
[2026-01-14T14:49:58Z] | snapshot-166137 | FAILED
[2026-01-14T15:48:51Z] | snapshot-166137 | SUCCESS (1m42.776204505s)
[2026-01-14T16:48:55Z] | snapshot-166154 | FAILED
[2026-01-14T17:47:20Z] | snapshot-166154 | SUCCESS (55.592177337s)
[2026-01-14T18:47:25Z] | snapshot-166164 | FAILED
Error Log:
Periodic Sync: Failed to sync Changed Block Tracking (CBT): failed to copy changed blocks: failed to connect to source: connect_uri: nbd_connect_uri: the server has no export named '': VixDiskLib_Open: [NA-SSD-LI-SHR-NE028] BLVSJOTHERS3V-apoj/BLVSJOTHERS3V-apoj_12.vmdk: The server refused connection: No such file or directory
What did you expect to happen?
expected the incremental copy to succeed on the first attempt for every new snapshot. The connection to the ESXi host should be established successfully immediately after the snapshot task completes.
Environment
v0.3.8
vCenter version
NA
Anything else you would like to add?
No response