I recently ran into this issue with VDP webclient not loading at a customer of mine. vCenter and PSC recently was updated to 6.0 U1. I believe its a vCenter or PSC permission issue and not specifically a VDP issue.
We looked at the webclient vergo logs at the time attempting to open the VDP webclient. Looks like the web client has an issue with com.vmware.vim.binding.vim.dvs.PortConnection which has to do with distributed switches.
[2016-04-06T17:50:42.280-05:00] [INFO ] http-bio-9443-exec-14 org.springframework.flex.servlet.MessageBrokerHandlerAdapter Channel endpoint vdp-amf received request.
[2016-04-06T17:50:42.367-05:00] [INFO ] http-bio-9443-exec-14 org.springframework.flex.servlet.MessageBrokerHandlerAdapter Channel endpoint vdp-amf received request.
[2016-04-06T17:50:42.382-05:00] [ERROR] http-bio-9443-exec-14 Endpoint.AMF Cannot create class of type 'com.vmware.vim.binding.vim.dvs.PortConnection'.
- flex.messaging.MessageException: Cannot create class of type 'com.vmware.vim.binding.vim.dvs.PortConnection'. Type 'com.vmware.vim.binding.vim.dvs.PortConnection' not found.
at flex.messaging.util.ClassUtil.createClass(ClassUtil.java:70)
Moving VDP from distributed switches to standard switches did get it to work and the errors disappeared in the vergo log. vCenter can still be connected to a distributed switch. Backup jobs continued to work when the webclient would not load.
It looks similar to this KB https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2125229 which is why I'm thinking its a vCenter or PSC permissions issue due to the upgrade. At this point we will probably wait for VMWare support to resolve the issue because for us moving VDP to a standard switch is an alright work around.
We also have an odd behavior with some of the roles displaying differently. For example there is a role called "inventorhyservice.tagging.taggingadmin" instead of "Tagging Admin". Might be related.