RabbitMQ Crash Explanation
<p>Our RabbitMQ service crashed twice with the following report in the $RABBITMQ_NODENAME-sasl.log:</p>

<pre><code>=CRASH REPORT==== 7-Jun-2016::14:37:25 ===
  crasher:
    initial call: gen:init_it/6
    pid: &lt;0.223.0&gt;
    registered_name: []
    exception exit: {{badmatch,
                         {[{msg_location,
                               &lt;&lt;162,171,39,113,226,229,228,92,227,253,48,186,
                                 45,48,29,98&gt;&gt;,
                               1,357,0,583},
                           ******************
                           16000 similar msg_location lines snipped
                           ******************
                          1795219}},
                     [{rabbit_msg_store,combine_files,3,[]},
                      {rabbit_msg_store_gc,attempt_action,3,[]},
                      {rabbit_msg_store_gc,handle_cast,2,[]},
                      {gen_server2,handle_msg,2,[]},
                      {proc_lib,wake_up,3,
                          [{file,"proc_lib.erl"},{line,250}]}]}
      in function  gen_server2:terminate/3
    ancestors: [msg_store_persistent,rabbit_sup,&lt;0.159.0&gt;]
    messages: [{'$gen_cast',{combine,394,380}}]
    links: [#Port&lt;0.86370&gt;,&lt;0.218.0&gt;,#Port&lt;0.86369&gt;]
    dictionary: [{{"/var/lib/rabbitmq/mnesia/$RABBITMQ_NODENAME/msg_store_persistent/357.rdq",
                    fhc_file},
                   {file,1,false}},
                  {{"/var/lib/rabbitmq/mnesia/$RABBITMQ_NODENAME/msg_store_persistent/340.rdq",
                    fhc_file},
                   {file,1,true}},
                  {fhc_age_tree,{2,
                                 {{1465,346244,764691},
                                  #Ref&lt;0.0.3145729.257998&gt;,nil,
                                  {{1465,346244,891543},
                                   #Ref&lt;0.0.3145729.258001&gt;,nil,nil}}}},
                  {{#Ref&lt;0.0.3145729.257998&gt;,fhc_handle},
                   {handle,{file_descriptor,prim_file,{#Port&lt;0.86369&gt;,59}},
                           0,false,0,1048576,[],false,
                           "/var/lib/rabbitmq/mnesia/$RABBITMQ_NODENAME/msg_store_persistent/357.rdq",
                           [raw,binary,read_ahead,read],
                           [{write_buffer,1048576}],
                           false,true,
                           {1465,346244,764691}}},
                  {{#Ref&lt;0.0.3145729.258001&gt;,fhc_handle},
                   {handle,{file_descriptor,prim_file,{#Port&lt;0.86370&gt;,64}},
                           14212552,false,0,1048576,[],false,
                           "/var/lib/rabbitmq/mnesia/$RABBITMQ_NODENAME/msg_store_persistent/340.rdq",
                           [raw,binary,read_ahead,read,write],
                           [{write_buffer,1048576}],
                           true,true,
                           {1465,346244,891543}}}]
    trap_exit: false
    status: running
    heap_size: 121536
    stack_size: 27
    reductions: 835024
  neighbours:
</code></pre>

<p>We'd like to understand what this crash report means.  Does it signify a bad message, RMQ can't find a message, or something completely different?  We're using RabbitMQ 3.1.5 with Erlang 18, and while we know we're using an old version, we want to first know what's causing the crash before dedicating resources to an upgrade.</p>