Major - P3 This will manifest also if profiling is enabled on the local db (since that causes explain to be run on the query to produce stats data).
Here is an example backtrace:
m31000| Assertion failed: (px != 0), function operator->, file src/third_party/boost/boost/smart_ptr/scoped_ptr.hpp, line 97. m31000| Got signal: 6 (Abort trap: 6). m31000| Backtrace: m31000| 0x100677a0b 0x10000190b 0x7fff88b2790a 0x4 0x7fff88b7ef61 0x7fff88b7fcb9 0x1003e4c56 0x1003b0636 0x100289399 0x100007134 0x10063db71 0x1006abe15 0x7fff88b39772 0x7fff88b261a1 m31000| 0 mongod 0x0000000100677a0b _ZN5mongo15printStackTraceERSo + 43 m31000| 1 mongod 0x000000010000190b _ZN5mongo10abruptQuitEi + 251 m31000| 2 libsystem_c.dylib 0x00007fff88b2790a _sigtramp + 26 m31000| 3 ??? 0x0000000000000004 0x0 + 4 m31000| 4 libsystem_c.dylib 0x00007fff88b7ef61 abort + 143 m31000| 5 libsystem_c.dylib 0x00007fff88b7fcb9 __assert_rtn + 146 m31000| 6 mongod 0x00000001003e4c56 _ZNK5mongo20SingleSolutionRunner7getInfoEPPNS_11TypeExplainEPPNS_8PlanInfoE + 334 m31000| 7 mongod 0x00000001003b0636 _ZN5mongo11newRunQueryERNS_7MessageERNS_12QueryMessageERNS_5CurOpES1_ + 7398 m31000| 8 mongod 0x0000000100289399 _ZN5mongo16assembleResponseERNS_7MessageERNS_10DbResponseERKNS_11HostAndPortE + 1961 m31000| 9 mongod 0x0000000100007134 _ZN5mongo16MyMessageHandler7processERNS_7MessageEPNS_21AbstractMessagingPortEPNS_9LastErrorE + 308 m31000| 10 mongod 0x000000010063db71 _ZN5mongo17PortMessageServer17handleIncomingMsgEPv + 1681 m31000| 11 mongod 0x00000001006abe15 thread_proxy + 229 m31000| 12 libsystem_c.dylib 0x00007fff88b39772 _pthread_start + 327 m31000| 13 libsystem_c.dylib 0x00007fff88b261a1 thread_start + 13