This is a common issue happened on the Mac users. 

Once Mac OS updated to a newer version or the update for Java, we found some users may experience the same issue even they've setup this before. 

But the new update may erase all the settings. For related similar case, just go to Java's website to test and active the Java on the browser.

Please kindly up the steps below:

 

For Safari Browser

Step 1: Go to Safari > Preference > Security. Enable plug-ins/Enable Java/Enable JavaScript.

For Safari 5.x:

 

For Safari 6.x:

Step 2: Go to Java's website: http://www.java.com/en/download/testjava.jsp and follow up the steps.

Step 3: Close the browser and restart the browser.

• For Firefox browser

Step 1: Go to Firefox > Tools > Add-ons option to enable Java plugin.

Step 2: Go to Java's website: http://www.java.com/en/download/testjava.jsp and follow up the steps.

Step 3: Click the plugin icon on the address bar, then click the Allow and Remember button.