QFuture throwing unhandled exception in result()

Question

I run 3 parallel threads (plus current thread) in a method to parallelize calls to na optimization method. Code looks like

 for(i=0;i<m+1;i++)
{ // run algorithms
    solverParallelData* parallelData = new solverParallelData(this); 

    for(j=0;j<m_ndim;j++) 
    {
        initPt[j] = initPts[i][j];
    }

    parallelData->runOptim(initPt);
    dataList.append(parallelData);
}

// retrieve results
solverParallelData *parallelDataRes;

try 
{
    for(int i = 0; i < dataList.size(); i++) 
    {
        parallelDataRes = dataList.at(i);

        int output = parallelDataRes->resultOptim();

              /*...*/
      }

where resultOptim() is a method in solverParallelData simply calling QFuture result(). The dataList seems to be filled properly. However, the line

  int output = parallelDataRes->resultOptim();

gives an unhandled exception which I cannot identify. Previouly, I had issues with concurrent access, and program crashes in QMutex class. Now I guess the source is different, but I cannot figure out what is wrong.

Thanks and regards.