From Firefox Version 52, (the standard version), the support to java plugin has ended, except for Adobe Flash.
Workaround (until 2018):
Install the 32bits of Firefox Version 52 ESR (Extended Support Release)
CI Server – Jenkins 2.23.2 LTS in Technosynoptic
Testing with the last version of JDK – jdk 1.8.0_u121 and Ubuntu 14.04.5 LTS
java version “1.8.0_121”
Java(TM) SE Runtime Environment (build 1.8.0_121-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.121-b13, mixed mode)
Running with own container
java -jar jenkins.war
The official guide from Apache
Migrating from 6.0.x to 7.0.x
Apache Tomcat 7.0.x requires Java 6 or later. Apache Tomcat 6.0.x required Java 5.
Details in https://tomcat.apache.org/migration-7.html
Tomcat 6 has now reached end of life.
Oracle JRE will no longer trust MD5-signed code by default
Beginning with the April 2017 Critical Patch Update, JAR files signed using MD5 (RSA algorithm) will no longer be considered as signed by the Oracle JRE.
Oracle Java SE 8u131 which will be released with the April 2017 Critical Patch Update.
Affected applications: Java applets, or Java Web Start applications.
To check your app/jar file:
jarsigner -verify -J-Djava.security.debug=jar mySynopticApp.jar
To remove any existing MD5 signatures first before re-signing using the zip utility as follows:
zip -d mySynopticApp.jar 'META-INF/*.SF' 'META-INF/*.RSA' 'META-INF/*.DSA'