After installing Veeam 9.5 Update 3a and simultaneous upgrade of vSphere from 6.5 to 6.7 Veeam vSphere Web Client Plugin might stop working for vSphere HTML5 Web Client. However it is still operational in vSphere Flash/Flex Web Client.
The issue is only reproducible in case the plugin was present on the vCenter prior to upgrade. The installation logs on vSphere side will show:
[<date and time>] [INFO ] vc-extensionmanager-pool-<id> 70000019 100003 200001 com.vmware.vise.extensionfw.ExtensionManager Plugin package com.veeam.backupui.VeeamBackupUi:188.8.131.522 was not deployed because attribute type="html" is missing, which is normal if this is a Flex plugin
The issue is caused by changes introduced in VMware vCenter Server 6.7.0a
Issue resolution requires complete plugin re-installation:
2) Remove plugin from VMware vCenter Server:
rm -r /etc/vmware/vsphere-client/vc-packages/vsphere-client-serenity/com.veeam.backupui.VeeamBackupUi-*/
rm -r /etc/vmware/vsphere-ui/vc-packages/vsphere-client-serenity/com.veeam.backupui.VeeamBackupUi-*/
3) Restart VMware services responsible for web-interface:
Either via appliance command line:
service-control --stop vsphere-client
service-control --stop vsphere-ui
service-control --start vsphere-client
service-control --start vsphere-ui
Or via Appliance Manager (port 5480) by restarting these services:
VMware vSphere Web Client
VMware vSphere Client
4) Install Veeam vSphere Web Client Plugin from Enterprise Manager.
5) Login to vSphere Web Client HTML5.
Please note the last step should be performed twice – on first login plugin will be installed, however, it will only appear after the second login.