Fixing slow vService Manager
This is about an issue I encountered in my lab recently. This issue affects vCenter version 8 U2 build 22617221
If you see that cloning VMs and powering on VMs takes forever and they get stuck at 95% and 66% respectively, but eventually finishes after an hour, you can check if you are affected by this issue.
Go to the task once it's finished, and check if this is shown in the task log:
Failed to retrieve OVF environment sections for VM <VM name> from extension vService Manager.
If you see that, you are affected by this issue.
A quick workaround is to restart the vService Manager service. You can do this by SSHing into the vCenter server, or going to vCenter on port 5480, then going to Services, look for the service and restart it.
I hope this is useful to someone, it was very useful to me. I haven't been able to find any documentation from VMware about this issue.