title: Crashed: WebThread - EXC_BAD_ACCESS KERN_INVALID_ADDRESS
body: <p>Since November 8, 2016, we've seen a sudden increase in crashes from WebThread.  We don't know what is causing the crash.</p>
  
  <p>We do have web articles and ads in the app. We did not have any App Release. There were no significant changes on the web or ads.</p>
  
  <p>Since crashes are happening on screens without articles, we are thinking it is happening on ads.</p>
  
  <p>Is anyone else seeing this?  Any thoughts, ideas, anything?</p>
  
  <p>Stack trace:</p>
  
  <pre><code>Crashed: WebThread
  0  WebCore                        0x184b7e47c WTF::HashMap&lt;WTF::String, WebCore::ApplicationCacheGroup*, WTF::StringHash, WTF::HashTraits&lt;WTF::String&gt;, WTF::HashTraits&lt;WebCore::ApplicationCacheGroup*&gt; &gt;::remove(WTF::String const&amp;) + 48
  1  WebCore                        0x184b7abbc WebCore::ApplicationCacheStorage::cacheGroupDestroyed(WebCore::ApplicationCacheGroup*) + 52
  2  WebCore                        0x184b7abbc WebCore::ApplicationCacheStorage::cacheGroupDestroyed(WebCore::ApplicationCacheGroup*) + 52
  3  WebCore                        0x184b70628 WebCore::ApplicationCacheGroup::~ApplicationCacheGroup() + 56
  4  WebCore                        0x184b70b10 WebCore::ApplicationCacheGroup::~ApplicationCacheGroup() + 12
  5  WebCore                        0x184b72334 WebCore::ApplicationCacheGroup::disassociateDocumentLoader(WebCore::DocumentLoader*) + 184
  6  WebCore                        0x184a024a0 WebCore::ApplicationCacheHost::~ApplicationCacheHost() + 48
  7  WebCore                        0x184a01ad0 WebCore::DocumentLoader::~DocumentLoader() + 168
  8  WebKitLegacy                   0x185976ba8 WebDocumentLoaderMac::~WebDocumentLoaderMac() + 84
  9  WebCore                        0x184e30a78 WebCore::FrameLoader::detachFromParent() + 324
  10 WebKitLegacy                   0x1859e0b08 __29-[WebView(WebPrivate) _close]_block_invoke + 348
  11 WebCore                        0x1857842c4 HandleRunSource(void*) + 368
  12 CoreFoundation                 0x180ab509c __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 24
  13 CoreFoundation                 0x180ab4ab0 __CFRunLoopDoSources0 + 412
  14 CoreFoundation                 0x180ab2830 __CFRunLoopRun + 724
  15 CoreFoundation                 0x1809dcc50 CFRunLoopRunSpecific + 384
  16 WebCore                        0x1849ce108 RunWebThread(void*) + 456
  17 libsystem_pthread.dylib        0x180763b28 _pthread_body + 156
  18 libsystem_pthread.dylib        0x180763a8c _pthread_body + 154
  19 libsystem_pthread.dylib        0x180761028 thread_start + 4
  </code></pre>