Error: "browser no longer supports the NPAPI plug-in" or "This Plugin is not supported" Edge SWG (ProxySG) or Advanced Secure Gateway

Products

• Advanced Secure Gateway Software - ASG
• ProxySG Software - SGOS

Issue/Introduction

Direct in-browser access to the Edge Secure Web Gateway (formerly ProxySG) or Advanced Secure Gateway (ASG) Java Management Console fails with messages "browser no longer supports the NPAPI plug-in" or "This Plugin is not supported".

Cause

NPAPI plugin support is required when a browser accesses the Edge SWG Java Management Console or the Proxy tab in the ASG Java Management Console directly.

Some browsers, such as Google Chrome and Mozilla Firefox, have removed support for the NPAPI plugin.

Refer to the following for the status of the NPAPI plugin support amongst browser versions:

 

Google Chrome

• NPAPI plugin support was disabled by default in version 42.  
• NPAPI plugin support was removed in version 45 and later.

Reference:

• https://www.chromium.org/developers/npapi-deprecation

 

Mozilla Firefox

• NPAPI plugin support was disabled by default in version 52.  
• NPAPI plugin support will be removed in version 53 and later.

Reference:

• https://bugzilla.mozilla.org/show_bug.cgi?id=1269807

Resolution

SG Admin Console

The SG Admin Console (SGAC) is the next-generation web interface for the Edge SWG appliance, designed to help you manage and monitor the appliance more efficiently. The Admin Console is the successor to the Java-based Management Console and can be accessed through the latest browsers.

The SG Admin Console does not have a dependency on Java or NPAPI.

Please refer to the SGAC documentation for more information.

 

Java Web Start Application

The Edge SWG supports launching applications with Java Web Start for all Management Console activities. These applications can be accessed using one of the following methods:

1. Navigate to the appliance's management console and click the link Java Network Launch Protocol (JNLP) file to download the legacy Java-based application. Open the downloaded file mc.jnlp with Java Web Start.
   
   
2. Navigate to the appliance's management console and click the link Launcher to download the Proxy Management Console Launcher, which enables you to save and manage multiple Edge SWG appliances. Open the downloaded file loader.jnlp with Java Web Start.
   
   
3. See Download the Management Console Launcher JNLP file to launch multiple Management Consoles to download the launchers from our Support site.
   
   

 

Legacy Browsers

Symantec supports browsers unaffected by NPAPI plugin removal that can access the Management Console directly, such as Internet Explorer 11.

See Supported Java, operating system, and browser versions for SGOS and Advanced Secure Gateway for more information on browser support.

If you are currently running Google Chrome version 42 through 44

NPAPI plugin support was disabled by default in versions 42 through 44.

To enable NPAPI plugin support:

1. In the browser address bar, enter: chrome://flags/#enable-npapi
2. In the Enable NPAPI section, click the Enable link.
3. At the bottom of the configuration page, click the Relaunch button to relaunch the browser.

If you are currently running Mozilla Firefox version 52

NPAPI plugin support was disabled by default in version 52.

To enable NPAPI plugin support :

1. In the browser address bar, enter: about:config
2. Add new Boolean string "plugin.load_flash_only" and set it to false.
3. Restart the browser.

Reference: http://www.omgubuntu.co.uk/2017/03/force-enable-firefox-52-npapi-support

NOTE: NPAPI support in Firefox ESR version 52 is not currently compatible with the Edge SWG or Advanced Secure Gateway Management Console.