title: java.lang.NullPointerException: Attempt to invoke virtual method 'void java.io.FileDescriptor.setInt$(int) error in Facebook Audience SDK
body: <p>I have integrated Facebook audience SDK </p>
  
  <blockquote>
    <p>'com.facebook.android:audience-network-sdk:5.1.0'</p>
  </blockquote>
  
  <p>in my project. Ad Showing properly in my device during debugging more but it crashing in the live version. Please note proguard is disable. A crash report is as per below.</p>
  
  <p><strong>java.lang.NullPointerException: Attempt to invoke virtual method 'void java.io.FileDescriptor.setInt$(int)' on a null object reference</strong></p>
  
  <blockquote>
    <p>java.lang.NullPointerException: Attempt to invoke virtual method
    'void java.io.FileDescriptor.setInt$(int)' on a null object reference
    java.net.PlainSocketImpl.accept(PlainSocketImpl.java:98) 
    java.net.ServerSocket.implAccept(ServerSocket.java:229) 
    java.net.ServerSocket.accept(ServerSocket.java:147)
    com.facebook.ads.internal.v.b.f.a(Unknown Source)
    com.facebook.ads.internal.v.b.f$e.run(Unknown Source)
    java.lang.Thread.run(Thread.java:833)</p>
  </blockquote>
  
  <p>I am getting this error in the Facebook Interstitial ad. How to resolve it?</p>