imessage crash

Hi,

When typing in a message or composing a new message (more commonly) on my Macbook Pro 2015 15" El Capitan 10.11.4, it keeps crashing with the exception listed below.

To isolate this issue I did a clean install with minimal apps I use and hoped it would fix the issue but it has not.

Problems:

• iMessage crashes seemingly randomly. Sometimes new message cause a lot of crashes, other times it happens only once in a while.
• When relaunching after a crash, normal text messages that were sent (confirmed on iPhone) show a "sending progress bar" as shown below. New text messages successfully sent (non-Imessage) do not have this behavior.

System information:

• Macbook Pro 2015 15" El Capitan 10.11.4, 16 GB Memory, AMD Radeon R9 M370X 2048 MB
• System Integrity Protection is off (I am a developer).

Process:               Messages [271]
Path:                  /Applications/Messages.app/Contents/MacOS/Messages
Identifier:            com.apple.iChat
Version:               9.2 (5100)
Build Info:            Messages-153000000000000~1
Code Type:             X86-64 (Native)
Parent Process:        ??? [1]
Responsible:           Messages [271]
User ID:               501

Date/Time:             2016-04-27 00:10:23.556 -0700
OS Version:            Mac OS X 10.11.4 (15E65)
Report Version:        11
Anonymous UUID:        -

Sleep/Wake UUID:       -

Time Awake Since Boot: 2900 seconds
Time Since Wake:       480 seconds

System Integrity Protection: disabled

Crashed Thread:        0  Dispatch queue: com.apple.main-thread

Exception Type:        EXC_CRASH (SIGABRT)
Exception Codes:       0x0000000000000000, 0x0000000000000000
Exception Note:        EXC_CORPSE_NOTIFY

4/28/16 12:39:08.707 PM Messages[5106]: *** Terminating app due to uncaught exception 'NSGenericException', reason: '*** Collection <__NSDictionaryM: 0x7fd05e5cacb0> was mutated while being enumerated.'
*** First throw call stack:
(
  0   CoreFoundation                      0x00007fff85c5b4f2 __exceptionPreprocess + 178
  1   libobjc.A.dylib                     0x00007fff88ed9f7e objc_exception_throw + 48
  2   CoreFoundation                      0x00007fff85cc215c __NSFastEnumerationMutationHandler + 300
  3   CoreFoundation                      0x00007fff85bcd1bb __NSDictionaryEnumerate + 811
  4   CoreFoundation                      0x00007fff85be838a -[NSDictionary keysOfEntriesWithOptions:passingTest:] + 234
  5   SocialUI                            0x00007fff8c0abc92 -[SOAddRecipientFieldViewController _queryIDSIMessageDestinations] + 167
  6   SocialUI                            0x00007fff8c0b1590 -[SOAddRecipientFieldViewController _updateAutoCompleteUI] + 2504
  7   SocialUI                            0x00007fff8c0ace92 __73-[SOAddRecipientFieldViewController autocompleteFetch:didReceiveResults:]_block_invoke + 256
  8   libdispatch.dylib                   0x00007fff8f5d893d _dispatch_call_block_and_release + 12
  9   libdispatch.dylib                   0x00007fff8f5cd40b _dispatch_client_callout + 8
  10  libdispatch.dylib                   0x00007fff8f5e0c1c _dispatch_main_queue_callback_4CF + 1685
  11  CoreFoundation                      0x00007fff85c109e9 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
  12  CoreFoundation                      0x00007fff85bcf8dd __CFRunLoopRun + 1949
  13  CoreFoundation                      0x00007fff85bceed8 CFRunLoopRunSpecific + 296
  14  HIToolbox                           0x00007fff95e53935 RunCurrentEventLoopInMode + 235
  15  HIToolbox                           0x00007fff95e5376f ReceiveNextEventCommon + 432
  16  HIToolbox                           0x00007fff95e535af _BlockUntilNextEventMatchingListInModeWithFilter + 71
  17  AppKit                              0x00007fff9238eefa _DPSNextEvent + 1067
  18  AppKit                              0x00007fff9238e32a -[NSApplication _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 454
  19  AppKit                              0x00007fff92382e84 -[NSApplication run] + 682
  20  AppKit                              0x00007fff9234c46c NSApplicationMain + 1176
  21  Messages                            0x0000000100b00bd1 main + 1717
  22  libdyld.dylib                       0x00007fff84e935ad start + 1
)

Some possible ideas I'm not sure how to test:

• Maybe a contact card is corrupt.
• SIP is off

I spend a lot of time and haven't fixed this issue. Any help would be appreciated!