I’ve honestly never had much luck installing the WebUI through the Task, and have always had to resort to installing it manually. You can work with Support to try to get it resolved, but if you need it soon or are up for experimenting you can try this.
On the BES Root Server, manually create the credential certificates for WebUI:
besadmin /createwebuicredentials /webuihostname=BFI-Win /webuicertdir=e:\BES-Keys\webui
Copy the new keys to the new WebUI server.
Get the WebUI installer file from the same URL from which the task is downloading it, and run it manually on the new WebUI server. When it asks for the credentials/keys, give it the path to which you’ve copied them.
I find that even when supplying the path, it doesn’t always create the target directory where they should go. So you may need to manually create the ‘cert’ folder beneath the WebUI directory and copy the keys there after installing, then restart the WebUI service.
The first service startup is going to take a long time as the root server has to gather new sites, and the WebUI server has to get them from your root server.
In the WebUI directory, check ‘service-wrapper.log’ for status info during early initialization. Note any messages there, especially if there’s anything about bad credentials or missing database connections.