When trying to make a particular update query (query.txt) over a stored document (storage.txt) the following error appear:(error.txt)

WriteConcern detected an error 'assertion src/mongo/db/storage/mmap_v1/btree/key.cpp:608'. (Response was { "connectionId" : 1006, "err" : "assertion src/mongo/db/storage/mmap_v1/btree/key.cpp:608", "n" : 0, "ok" : 1.0 }). 
Type: MongoDB.Driver.WriteConcernException

I realized that this only happens when the query have the exact field name "size_of_raw_data" with value 512. If i change the value to 513 or 511 or whatever else, the query executes in normal way.