Download plug-in failed in vSphere Client with error "Error downloading plug-in"

Products

• VMware vCenter Server

Issue/Introduction

Getting the following error in vSphere Client:

Error downloading plug-in. Make sure that the URL is reachable and the registered thumbprint is correct.

Environment

• VMware vCenter Server 7.0.x
• VMware vCenter Server 8.0.x
• VMware vCenter Server 9.0.x

Cause

• One or more plugins failed to communicate with vCenter Server.
• This issue occurs when the vCenter Server cannot establish a bidirectional connection to the plugin's source appliance (e.g., VCF Operations) over port 443 (HTTPS).

Resolution

1. On the vSphere Client > Administration > Solutions > Client Plugins page, click the plugin that cannot communicate with vCenter Server.
2. If the plugin is deprecated, click REMOVE to remove it from vCenter Server.
3. If the plugin is in use, make sure vCenter Server is able to access its URL:
   • Check if the IP address or FQDN is accessible from vCenter Server
   • Check the plugin Docs to see if it requires access to a specific port on vCenter. If so, verify the connectivity from the plugin admin console to vCenter Server on the port.