Feeling the need to vent here about something that I consider shockingly basic.
I upgraded from vCenter 6 to 6.5. Had to reconnect my hosts after the upgrade. Didn't think anything of it, then the nightly backup failed. Not the biggest deal I thought, I'll be able to remap them or something, no you can't remap them in a backup. Telling it to recalculate is now telling me 0 bytes to backup. Remove and re-add the VMs to the backup job and use the map backup button. Check when the nightly job is running and it's processing all the data again, initially I'm thinking this is okay maybe it's a CBT reset due to all this, then I look into my backups and I can see it's making duplicate entries of all my VMs! So 6TB extra disk space wasted later on another full backup and it comes to the turn of my backup copy job. No surprises that it decides to copy all 6TB of backup over my 100Mb link again. So nearly 14 hours later and it's on 1%. At this point I feel the need to add the moment I had the problem with object not found I started searching Veeam's knowledge base but it was only giving me messages to do with Veeam 6.x and 7.x nothing to do with the migration tool.
I called up Veeam technical support and they've said that because the VM references are different this happens. I can't get my head around how you can do replica mapping where VMs can be on complete different data centers with different references and yet still map however you can't do an incremental backup after mapping an existing backup and then have to clone all the VMs again.
Then after speaking to Veeam technical support they've told me to use the Veeam Migration tool which is the first I've seen of it and was told to just cancel my backup copy job etc. But then reading the KB article because the backup ran I now can't.
So I'm stuck wasting an additional 12TB of backup storage between my DC's to preserve my backup chains, either got to start doing a backup to disk and then try to seed it to the other site or wait for it to run which'll likely take another week and got Veeam technical support telling me to run a tool even after I've told them that a backup has already run. All because a feature such as map backup doesn't do anything you'd expect it to and they've got a vCenter migration tool sat as a separate tool in a KB rather than integrated into Veeam itself to deliver a supported reconnect scenario.
Really disappointed in this. Been using Veeam for years now and never had it blow up on me as dramatically as this before. Done vSphere 5 to 5.5, 5.5 to 6 and expanded to multiple vCenter with no issues, worked all the way from Veeam 6 to 9.5 then another trivial vCenter upgrade and suddenly my backup window is destroyed and the Veeam support team are just telling me I'm out of luck or telling me to use unsupported tools in conditions their KB is strongly advising against.
Case # 02195767 if anyone from Veeam wants to look into it though I imagine it's all too far gone to save this time.