I need to access a corporate application that has a web interface and a Java applet.
I read that Firefox 52 and later don't allow the Java plugin anymore. So I installed Firefox Portable 51.0.1 into C:\users\username\Downloads\Firefox_51.0.1_Portable\FirefoxPortable. Then I copied the FirefoxPortable.ini file from the Other\Source directory and put it in the same directory as FirefoxPortable.exe. I edited the file to have the following:
Then I read that Java 8u131 and later don't allow MD5 signed jar files which the corporate application uses. So I installed the 32-bit version of JPortable 8u121 into C:\Users\username\Downloads\Firefox_51.0.1_Portable\CommonFiles\Java. (followed the instructions at https://portableapps.com/support/firefox_portable#plugins)
I launched FirefoxPortable.exe, and checked the Tools->Add-ons->Plugins, and I saw that it had the Java(TM) Platform SE 8 U121 plugin. Looks like I installed everything correctly.
But when I go to https://www.java.com/verify/ and click on "Verify Java Version" to make sure the Java plugin is working, it says "Detecting Java on your computer" and "The Java detection app will ask for permission to run. Click Run to allow the verification process to continue. Depending on your system settings, you may need to respond to prompts to allow the verification to continue."
But it doesn't prompt me at all. After about 2 minutes, it finally says:
"We are unable to verify if Java is currently installed and enabled in your browser."
I also went into the Java Control Panel, to the Security tab, made sure "High" was selected, and then added "https://www.java.com/" into the Exception Site List, but that didn't help.
EDIT: I got it working. Somehow the "Enable Java content in the browser" box wasn't checked in the Security tab of the Java Control Panel, and also I needed to have the port number along with the URL in the Exception Site List.