serialization - Intermittent Exception when Deserializing Data Using Memory Mapped Files in C# -

i'm getting exception when deserializing data using memory mapped files , i'm not quite sure why.

here's important parts of code:

//the class serializing [protocontract] public class result {     [protomember(1)]     private dictionary<string, string> _errordict;     [protomember(2)]     public dictionary<string, string> resultsdict { get; set; }      private readonly pipestream _stream;     private readonly streamwriter _writer;     private memorymappedfile _mmf;      public result()     {         _errordict = new dictionary<string, string>();     }     public result(string pipehandle)     {         _errordict = new dictionary<string, string>();         resultsdict = new dictionary<string, string>();         if (pipehandle != null)         {             _stream = new anonymouspipeclientstream(pipedirection.out, pipehandle);             _writer = new streamwriter(_stream) { autoflush = true };         }     }      public void adderror(string file, string error)     {         _errordict.add(file, error);     }      public void serialize()     {         _mmf = memorymappedfile.createoropen(frconfig.config_file, frconfig.config_file_size);         using (memorymappedviewstream stream = _mmf.createviewstream())         {             serializer.serializewithlengthprefix(stream, this, prefixstyle.base128);             stream.flush();         }     }      public static result deserialize()     {         using (memorymappedfile mmf = memorymappedfile.openexisting(frconfig.config_file))         {             using (memorymappedviewstream stream = mmf.createviewstream())             {                 return serializer.deserializewithlengthprefix<frresult>(stream, prefixstyle.base128);             }         }     }      /// <summary>     /// writes progress information pipe.     /// </summary>     public void writetostream(object s)     {         if (_stream == null || _writer == null) return;         _writer.writeline(s);         _stream.waitforpipedrain();     } }  //on main thread: private static void main() {     //spawn child process     //after returning child process...     var r = frresult.deserialize(); }  //on child process static void main(string[] args)  {     var result = new frresult(pipehandle);     //perform processing     result.serialize() } 

when making call deserialize method after returning child process, somethimes following exception:

filenotfoundexception occured exception thrown: 'system.io.filenotfoundexception' in system.core.dll additional information: unable find specified file.

system.io.filenotfoundexception occurred
hresult=-2147024894
message=unable find specified file.
source=system.core
stacktrace:
@ system.io.__error.winioerror(int32 errorcode, string maybefullpath)
innerexception:

i'm not sure why error gets thrown nor best way fix this.