Omnissa Horizon Web Client Release Notes

Horizon Web Client 2503.2 | 09 JUL 2026

This page is revised periodically as needed with information about the Horizon Web Client 2503.2, which enables users to connect to and use remote desktops and published applications through a supported web browser. Check back regularly for additions and updates to these release notes.

What's New

Horizon Web Client 2503.2 is released along with the Horizon 8 2503.2 release. This release includes enhanced validation checks and workflow improvements to Lifecycle Management (LCM) operations, improving reliability and user experience.

The Horizon Web Client 2503.2 release does not contain any Hot Patches that were provided in versions before 2503.2.

Before You Begin

For a list of the supported browsers, supported client operating systems, Web Client system requirements, and installation instructions, see the Horizon Web Client Guide.
Horizon Web Client 2503 supports Horizon Agent 2503.
Horizon Web Client is supported with the latest maintenance release of the following deployment types:
- Horizon 8 version 2006 and later
- Horizon Cloud Service - next-gen
- Horizon Cloud in Microsoft Azure
With Horizon Web Client 2503 and Horizon 8 version 2503, if you connect to a server through a load balancer or a gateway, such as F5 or Unified Access Gateway, you must first configure a security setting in Horizon. For more information, see "Origin Checking" in the Horizon Security guide.

Resolved Issues

There are no major issue resolutions to report in this release.

Known Issues

The following sections describe known issues related to the operation and performance of Horizon Web Client.

For known issues specific to the use of Horizon Web Client in a Horizon Cloud Service - next-gen environment, see the Horizon Cloud Service - next-gen Release Notes.

Audio and Video

Lag in audio-video synchronization
Horizon Web Client might experience a lag in audio-video synchronization. The lag might be due to network conditions, hardware performance, device type, or another cause.

Workaround: None. This issue will be fixed in an upcoming release of Horizon Web Client.
Audio problems when switching media source in iOS Safari
On iOS Safari, if you connect to a remote desktop and play audio or video on the remote desktop, and switch to playing audio or video with a native application without disconnecting from a Connection Server instance, and switch back to the remote desktop on Safari, audio no longer works.

Workaround: Disconnect or log off from the Connection Server instance and connect to the remote desktop again.
Web Audio API support is required for optimal sound quality
Sound playback quality is best on browsers that have Web Audio API support. Chrome, Safari, and Firefox 25 and later browsers have Web Audio API support. Browsers that do not have this support include Firefox 24 and earlier.

Workaround: None
Audio processing becomes intermittent
On Chrome, Safari, and Edge browsers, if audio is playing and you switch to another tab in the browser or minimize the browser, audio processing becomes intermittent. After you re-focus on the remote desktop tab, audio might be out of sync with video for a few seconds.

Workaround: Refresh the page or pull the remote desktop's tab out of the browser so that it has its own window.
Problems with repeat redirection in macOS Chrome
Occasionally, Real-Time Audio-Video (RTAV) video redirection does not work when you use it for a second time with Chrome on a macOS system.

Workaround: Refresh the browser.
Problems when exiting multiple-monitor mode The Web browser from which you start a desktop might stop responding if you repeat the following steps multiple times: enter multiple-monitor mode, open Real-Time Audio-Video (RTAV), move the camera window to the second display, exit multiple-monitor mode, or start another remote desktop from the sidebar.

Workaround: None.
Problems when unplugging extended monitor The sidebar, and sometimes the remote desktop, disappears after you unplug the extended display monitor while using the multiple monitor feature with a Chrome Web browser.

Workaround: Restart HTML Access, resize the application window, or re-plug the extended display monitor.
Warning message in Safari 12
In Safari 12, the first time you open a remote desktop or published application, a warning message instructs you to enable audio. This warning message appears again after you log out from the server, close or refresh the browser, and open a remote desktop or published application.

Workaround: None.
Teams Media Optimization becomes unavailable after a network interruption
The Media Optimization for Microsoft Teams feature is unavailable after a network interruption occurs on the client session. For details, see the Omnissa Knowledge Base (KB).

Workaround : None.

Browsers

Empty sessions when using Chrome
When using Chrome version 67 or later, you might receive an empty session after you start a remote desktop, enter multiple-monitor mode, move the mouse pointer to the second display monitor, and exit multiple-monitor mode.

Workaround: Manually resize the Chrome window or refresh the page.
Problems with Linkclump Chrome extension and right-click behavior
The Linkclump Chrome extension interferes with proper right-click behavior. If you right-click text in a remote desktop, the right-click might behave as a left-click-and-drag action.

Workaround: Disable the extension, or go into the Chrome Linkclump Options page and enter the address of the Connection Server instance in the Blocklist section.
Problems when using Chrome browser
When you use HTML Access in a Chrome browser, you might encounter the following problems:
- Occasionally, when connecting to a remote desktop or published application after the session has timed out, a "Failed to connect the Connection Server" error message appears.
- A session is not opened when you connect to a powered off desktop.
Both problems have the same root cause, which is a third-party issue.

Workaround : For the first problem, dismiss the error message and reconnect to the remote desktop or published application. For the second problem, reload the browser or reconnect to the remote desktop.

Connectivity

Desktop sessions are disconnected in Firefox
When using a Firefox browser, your Horizon Web Client remote desktop session is disconnected immediately after connecting.

Workaround : Verify that your Firefox browser proxy settings are configured correctly.
Suspension of remote desktops does not work
Do not configure remote desktops to be suspended after users disconnect. This setting does not work correctly with HTML Access.

Workaround: None
Blast Secure Gateway causes failed connection to remote desktop or published application
Connecting to a remote desktop or published application fails if Blast Secure Gateway (BSG) is enabled on both the Unified Access Gateway server and the Connection Server instance.

Workaround: Disable BSG on the Connection Server instance.
Problems when Enable Blast is set to False in Unified Access Gateway
In Unified Access Gateway, if you set the Enable Blast Horizon Edge setting to False, you cannot access remote desktops and published applications through Horizon Web Client. Generally, because Unified Access Gateway is deployed in a DMZ, the Enable Blast option is set to True and this issue does not occur.

Workaround: In Unified Access Gateway, if you set Enable Blast to False and also use Horizon Web Client, set the proxyPattern option to "/|/portal(.*)".
Unified Access Gateway server session timeout is not recognized
If you access a remote desktop or published application through HTML Access that is connected with a Unified Access Gateway server, the remote desktop or published application session is not disconnected after the Unified Access Gateway server session timeout is reached.

Workaround: None.

Security

Problems with RDS Per Device Client Access Licenses
Do not use RDS Per Device Client Access Licenses (CALs) for Horizon Web Client. If you do, the licensing mechanism treats each browser as a device, and, if cookies are cleared, the browser uses another license.

Workaround: Use RDS Per User CALs for HTML Access.
Unified Access Gateway server self-signed certificate does not work on Chromebook
On a Chromebook, when connecting to a Unified Access Gateway server that uses a self-signed certificate, HTML Access reports the error ERR_CERT_INVALID.

Workaround: Install a CA-signed certificate on the Unified Access Gateway server.
Self-signed certificates are not supported on iOS
On iOS, if you attempt to connect to a remote desktop by using a self-signed certificate, Safari reports the error "Your desktop has been disconnected. Unable to reconnect to desktop." This problem occurs because self-signed certificates are not supported on iOS.

Workaround: An administrator must install a CA-signed certificate on the Connection Server, and you must trust the certificate on your iOS device. For information about installing certificates on Connection Server, see the Horizon 8 Administration guide. For information about trusting certificates on an iOS device, see the Horizon HTML Access Guide. If the Blast Secure Gateway is disabled on the Connection Server, an administrator must perform the following additional steps on the remote desktop to connect from iOS:
1. Use mmc to import the CA-signed certificate into the Windows certificate store.
2. Replace the sslHash key in HKEY_LOCAL_MACHINE\SOFTWARE\Omnissa\Horizon Blast\Config with the key from the thumbprint of the certificate issued to the Blast Agent Hostname or IP address.
3. Restart the Blast Agent virtual machine.
Cached credentials fail to clear
When the Clean up credential when tab closed for HTML Access global setting is enabled in Horizon, the cache is not cleared if a user closes a tab when the network connection is not available.

Workaround: None.
Application fails to restart automatically after password change
After an administrator sets the change password at next logon option for a user's account, and the user's idle session times out, the application that was active during the session timeout is not restarted automatically after the user reauthenticates and changes the password successfully.

Workaround: Refresh the page and launch the application again from the sidebar.
Problems with intermediate CA-signed certificates in iOS
Remote desktops and published applications cannot be started successfully from an iOS device if the iOS device uses an intermediate CA-signed certificate.

Workaround: Install a root CA-signed certificate on the iOS device.
Problems with Unified Access Gateway self-signed certificate and Microsoft Edge
If you use a self-signed certificate with Unified Access Gateway, you might not be able to access a remote desktop when you use a Microsoft Edge Web browser for the HTML Access session.
Workaround: Use one of the following workarounds to resolve this issue.
- Use a valid CA-signed certificate.
- Do not use port 8443 for the Blast External URL property. Use port 443 instead.
Remote desktop connection fails with Microsoft Edge
If you configured Unified Access Gateway with a root certificate that is signed by a Certificate Authority (CA), and the Blast External URL property value is set to blank or to port 8443, you might not be able to connect to a remote desktop if you are using a Microsoft Edge browser. After the error occurs, all new connected sessions are not visible.
Workaround: Use one of the following workarounds to resolve the issue.
- Set the Blast External URL property to port 443.
- Close the Microsoft Edge browser, restart the HTML Access, and connect to the remote desktop.

Miscellaneous

ARM CPUs are not supported
HTML Access is not supported on client systems running on ARM-based CPUs, such as:
- Mac system with M1 or M2 chips
- Windows system with ARM-based CPU
An incompatibility warning appears if you attempt to use HTML Access from such a client system. Bypassing this warning is not recommended.

Workaround: Install and use a native client instead. URI launch from native clients is supported on systems with ARM-based CPUs.
Japanese keyboard mapping is incorrect
When you connect to a Linux desktop with the Japanese keyboard, the keyboard mapping might be incorrect. For example, the key positions\| and\_ will be incorrect.

Workaround: Keep the client input language as Japanese and switch the desktop input language to English for the two key positions \| and\_ only. Keep the desktop input language as Japanese and switch the client input language to English for all other key positions.
Keyboard input does not work in Linux desktop sessions
When connecting to a Linux desktop, some keyboard input does not work. For example:
- The * key on the numeric keypad is displayed as 8.
- English keyboard: the + key on the numeric keypad is displayed as =.
- Non-English IME on both client and desktop: some non-English keys are not displayed correctly.
Workaround: For issues 1 and 2, use the typewriter keys * and + in the main keyboard area instead of the numeric keypad. For issue 3, set English IME in HTML Access and non-English IME on the remote desktop.
Autofit of published applications does not work
Intermittently, autofit of a published application does not work. This problem can happen if you start a published application and activate full-screen mode for the browser, start a published application from the sidebar and activate full-screen mode, or start a published application and enlarge the size of the browser window.

Workaround: Activate full-screen mode or resize the browser window before starting a published application.
Locked desktop session still allows file upload
Users can still upload files when the remote desktop is locked.

Workaround: None.
Problems with clipboard format restrictions
When an administrator enables a clipboard format restriction, the text in the Copy & Paste window does not describe the format limitation. For example, if an administrator enables the "Filter text out of the incoming clipboard data" clipboard policy setting, the Copy & Paste window does not notify the user that text cannot be transferred from the client to the remote desktop or application.

Workaround: None.

Double mouse cursors in multiple-monitor mode
In multiple-monitor mode, two mouse cursors appear when you click inside a remote desktop or published application session.

Workaround : None.

Scroll bars are hidden when using Session Collaboration on macOS
When you use a Web browser on a macOS 10.13 system in a Session Collaboration collaborative session, if Fit to Viewer is disabled and the collaborative session's screen resolution is less than the primary session's screen resolution, a scroll bar does not appear. This issue occurs because scroll bars are hidden by default in macOS 10.13 systems.

Workaround: Modify the System Preferences to always display scroll bars.
1. Choose Apple menu > System Preferences.
2. Click General.
3. In the Show scroll bars section, select Always.
Problems with H.254 decoding in Chrome
When the Allow H.264 decoding option is enabled, a newly started published application fails to open and the remote session shows a black screen.

Workaround : Resize the Chrome browser.
Problems when using software keyboard
When you start HTML Access from a Chrome Web browser on an Android 8.1 device, or from a Safari Web browser on an iOS 11 device, the remote desktop window sometimes disappears while you are using the software keyboard in a remote session. This issue often occurs when you are rotating the device and then closing and reopening the software keyboard. After the error has occurred, all subsequent remote desktop sessions opened are not visible.

Workaround: Reload the Web browser page.
Smart Policy changes fail to take effect upon reconnecting to session
Smart Policy changes do not take effect immediately after reconnecting to a remote desktop. After you change the Smart Policy Clipboard and File Transfer from Allow all to Disable , the functions are deactivated, but the text for the Copy & Paste window shows the incorrect text. Also, if you are connected to a remote desktop from an HTML Access session when the Smart Policy Clipboard and File Transfer setting is changed and you disconnect, the changes do not take affect after you reconnect to the remote desktop.

Workaround: Log off from the remote desktop and reconnect to the remote desktop, then disconnect from the remote desktop and reconnect to the remote desktop again.
Problems when switching between sessions with H.264 decoding
When H.264 decoding is enabled, if you use the sidebar to switch between remote desktops, or between remote desktops and published applications, the remote sessions become unresponsive. The remote sessions are still connected, but mouse clicks and other actions do not work.

Workaround: Close and reconnect to the remote desktop or published application sessions.

Documentation

Horizon HTML Access documentation is in the Omnissa Information Hub.

Localized Content for Omnissa Docs

For details on Omnissa's localization strategy, see the article "Announcing Omnissa Localization Support".

Support Contact Information

To receive support and to learn more about support policies, see Omnissa Customer Connect.

For information on filing a support request in Customer Connect and through the Cloud Services Portal, see the Omnissa knowledge base article at https://kb.omnissa.com/s/article/2006985.

Was this page helpful?