Applet throws java.lang.IllegalArgumentException: invalid action string in Java8

Question

Our applet throws the following exception on the java8 platform (jre 1.8._0.31). The problem seems the same on this issue , but one big difference is this exception caused by the plugin code block, not our code block. I think the plugin is trying to load the application jar and failed. Our applet is not signed, but the domain where it works is in "Editing the list of sites." In addition, another unsigned applet in the same domain works without problems.

    cache: Resource http://xyz.com.tr/MyWeb/applauncher.jar has expired.
    enter basic: exception: invalid actions string.
java.lang.IllegalArgumentException: invalid actions string
    at java.net.URLPermission.init(Unknown Source)
    at java.net.URLPermission.<init>(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.URLtoSocketPermission(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
    at com.sun.deploy.net.HttpUtils.followRedirects(Unknown Source)
    at com.sun.deploy.net.BasicHttpRequest.doRequest(Unknown Source)
    at com.sun.deploy.net.BasicHttpRequest.doGetRequestEX(Unknown Source)
    at com.sun.deploy.cache.ResourceProviderImpl.checkUpdateAvailable(Unknown Source)
    at com.sun.deploy.cache.ResourceProviderImpl.isUpdateAvailable(Unknown Source)
    at com.sun.deploy.cache.DeployCacheHandler.get(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection$6.run(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection$6.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessController.doPrivileged(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.connect(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.access$200(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection$9.run(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection$9.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessController.doPrivileged(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
    at sun.plugin.PluginURLJarFileCallBack.downloadJAR(Unknown Source)
    at sun.plugin.PluginURLJarFileCallBack.access$000(Unknown Source)
    at sun.plugin.PluginURLJarFileCallBack$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.plugin.PluginURLJarFileCallBack.retrieve(Unknown Source)
    at sun.net.www.protocol.jar.URLJarFile.retrieve(Unknown Source)
    at sun.net.www.protocol.jar.URLJarFile.getJarFile(Unknown Source)
    at sun.net.www.protocol.jar.JarFileFactory.get(Unknown Source)
    at sun.net.www.protocol.jar.JarURLConnection.connect(Unknown Source)
    at sun.plugin.net.protocol.jar.CachedJarURLConnection.connect(Unknown Source)
    at sun.plugin.net.protocol.jar.CachedJarURLConnection.getJarFileInternal(Unknown Source)
    at sun.plugin.net.protocol.jar.CachedJarURLConnection.getJarFile(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath$JarLoader.getJarFile(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath$JarLoader.access$800(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath$JarLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.deploy.security.DeployURLClassPath$JarLoader.ensureOpen(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath$JarLoader.<init>(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.deploy.security.DeployURLClassPath.getLoader(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath.getLoader(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath.getResource(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader$2.run(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader$2.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.plugin2.applet.Plugin2ClassLoader.findClassHelper(Unknown Source)
    at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager.initAppletAdapter(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)