Applet fails loading and throws a NullPointerException

According to the Release Notes of Java 7 Update 45, the applet could fail to load by throwing a NullPointerException, if caching is disabled.

The SignLive! CC cloud suite applets use two Manifest attributes (Permissions and Caller-Allowable-Codebase), which enforce, that Jar caching must be enabled in the Java Control Panel. Otherwise the applet will fail loading.

If a JAR file is using pack compression with manifest entries Permissions and Caller-Allowable-Codebase while deployment caching is disabled, then:
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The Caller-Allowable-Codebase attribute will cause the applet to fail to load by throwing a java.lang.NullPointerException.

Source Java 7 Update 45 Release Notes.