Horizon Client — Black/Blank Monitor Display
Introduction
If a user sees a blank or black screen when launching the Horizon Client, several factors may contribute to the display. This article explains some of the most common causes of the Horizon black screen and provides corresponding solutions.
This troubleshooting guide applies to Horizon 8.
Causes of a blank/black screen
Various factors can cause a blank or black screen when connecting to Horizon View and establishing a VDI session.
Required Network Ports
For the Horizon Client to function properly, ensure the required ports are accessible.
The following ports are required when the Horizon Client connects directly to a Connection Server:
| Destination | Network Protocol | Destination Port | Details |
|---|---|---|---|
| Connection Server | TCP | 443 |
Login, authentication, and connection to the connection server |
| Horizon Agent | TCP | 22443 |
Blast Extreme |
| UDP | 22443 |
Blast Extreme | |
| TCP | 4172 |
PCoIP | |
| UDP | 4172 |
PCoIP | |
| TCP | 9427 |
Drive Redirection (CDR) and Multimedia Redirection (MMR) | |
| TCP | 32111 |
USB redirection (optional, can be integrated into Blast Extreme) |
The following ports are required when the Horizon Client connects via a Unified Access Gateway (UAG):
| Destination | Network protocol | Destination port | Details |
|---|---|---|---|
| Unified Access Gateway | TCP | 443 |
Login, authentication, and connection to the UAG. It may also carry tunneled RDP, CDR, and USB traffic. |
| TCP | 4172 |
PCoIP via PCoIP Secure Gateway | |
| UDP | 4172 |
PCoIP via PCoIP Secure Gateway | |
| UDP | 443 |
Use it optionally for login traffic. If TCP conditions are suboptimal, Blast Extreme attempts a UDP connection. | |
| TCP | 8443 |
Blast Extreme via Blast Secure Gateway (High-performance connection) | |
| UDP | 8443 |
Blast Extreme via Blast Secure Gateway (Customized Performance Option) | |
| TCP | 443 |
Blast Extreme via UAG Port Sharing |
DNS Considerations
While Horizon View typically uses IP addresses for communication between the Connection Server, DNS issues can affect component performance.
Therefore, always ensure DNS functions correctly both internally and externally.
Correctly configure Unified Access Gateway (UAG).
A common cause of a black screen is an incorrectly configured Unified Access Gateway (UAG) for Horizon.
Configuration errors between the Connection Server and the UAG often occur during initial setup.
When configuring a UAG, disable both Blast Secure Gateway and PCoIP Secure Gateway on the Connection Server, as the UAG handles these functions.
Secure Gateway Settings When Using UAG
Another common issue occurs when the Unified Access Gateway (UAG) is misconfigured. Several important parameters must be set correctly. Enter the following values under Horizon Settings on the UAG:
| Setting | Value |
|---|---|
| Connection Server URL | https://ConnectionServerIP:443 |
| Connection Server URL Thumbprint | sha1=SSLTHUMPRINT (Thumbprint of the View Connection Server’s SSL certificate) |
| PCOIP External URL | UAG-EXTERNALIP:4172 |
| Blast External URL | UAG-InternetFQDN:443 |
| Tunnel External URL | UAG-InternetFQDN:443 |
Additionally, install a valid SSL certificate under TLS Server Certificate Settings. Apply this certificate to both the admin and internal interfaces. Ensure the certificate matches the FQDN (internal and external) of the UAG appliance.