When loading the vSphere client to a vCenter that has a Zerto Virtual Manager connected, the Zerto tab doesn't appear on any of the vCenter objects (VC Server, virtual Datacenter, host cluster, ESXi host, virtual machine, etc)
When loading the Plug-In Manager, the Zerto Virtual Replication Plugin shows the error:

  • The following error occurred while downloading the script plugin from https://<ZVM_IP>:9669/ZvmService/GuiPageServer/pubsplugin.xml: The client could not send a complete request to the server. (The underlying connection was closed: An unexpected error occurred on a send.)


To resolve, it will be necessary to ensure that TLS 1.0 has been enabled on the ZVM server. To do this, a 3rd party utility can be used. IISCrypto, available at, can be used to determine the Windows cryptographic settings configured on the ZVM Server. For the plugin to load properly, TLS 1.0 should be enabled. If the checkbox is not activated, toggle it, save the settings, and reboot the ZVM server.

Alternatively, this protocol can be enabled manually through the registry:

  • On the ZVM server, open the registry
  • Navigate to the path HKLM\System\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols
  • Create a subkey under Protocols called "TLS 1.0"
  • Under this new subkey, create another subkey called "Server"
  • Under this subkey, create a DWORD value called "DisabledByDefault", and set the value to 0
  • Create a second DWORD value called "Enabled", and set the value to 0xffffffff

Once the above changes have been made, reboot the ZVM server. More information on the above registry entries may be found at

Affected versions: