title: Getting a weird ClassNotFoundException in ac.loadClass
body: <p>I have an active app on Google Play. My users are often experiencing a crash that I can't figure out where to debug.</p>
  
  <pre><code>java.lang.NoClassDefFoundError: 
    at jl.b (jl.java:3)
    at jk.a (jk.java:3)
    at jm.a (jm.java:18)
    at com.google.android.gms.ads.internal.util.ap.a (ap.java:17)
    at ip.a (ip.java:19)
    at ip.run (ip.java:8)
  Caused by: java.lang.ClassNotFoundException: 
    at dalvik.system.BaseDexClassLoader.findClass (BaseDexClassLoader.java:134)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:379)
    at ac.loadClass (ac.java:4)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:312)
    at jl.b (jl.java:3)
    at jk.a (jk.java:3)
    at jm.a (jm.java:18)
    at com.google.android.gms.ads.internal.util.ap.a (ap.java:17)
    at ip.a (ip.java:19)
    at ip.run (ip.java:8)
  </code></pre>
  
  <p>The last portion makes me think it's related to AdMob</p>
  
  <pre><code>at com.google.android.gms.ads.internal.util.ap.a (ap.java:17)
  </code></pre>
  
  <p>But I can't figure out where's exactly the problem. Everything on my test devices seem to be fine, but still other users are experiencing these crashes.</p>
  
  <p>I've uploaded the de-obfuscator file, but these stack traces are all obfuscated.</p>
  
  <p>I'm currently using the version 16.0.0 of play services ads</p>
  
  <pre><code>implementation 'com.google.android.gms:play-services-ads:16.0.0'
  </code></pre>