Beginning with Firefox 52, NPAPI plugin support will be limited to Flash support. Java plug-in will no longer be supported. Due to this change, JSAM and any additional Java Applet client delivery options for PCS application access that rely on Java plug-in support will no longer work with Firefox 52+. For more information, please refer to https://java.com/en/download/help/firefox_java.xml
As a proactive step, Pulse Secure blocked Java (including JSAM) for Firefox browsers starting in PCS OS 8.2R5 to 8.2R7. With the release of 8.2R8 (tentative for end of May 2017), the block was removed and end users are able to launch JSAM for Firefox 52.X Extended Support Release (ESR) and previous versions of Firefox that still support the Java plugin.