FCN not being able to resume

So I have performed some training on my data, and wanted to test my solution half-way through running training of FCN network for semantic segmentation. However, I got this error:

Error using trainNetwork (line 140)
The last layer must be an output layer.

Error in neural2 (line 93)
    [sp, info] = trainNetwork(datasource,war.Layers,options);

Caused by:
    Error using nnet.internal.cnn.layer.util.inferParameters (line 7)
    The last layer must be an output layer.

What I have done is just loaded that checkpoint and tried to run training on it again, but that failed. Below is a short piece of my code with else statement not working:

imageSize = [227 227];
numClasses = numel(classes);
lgraph = fcnLayers(imageSize,numClasses,'type','16s');
st = fullfile('imade','checkPoint');

datasource = pixelLabelImageSource(imdsTrain,pxdsTrain);

doTraining = true;

if doTraining
    options = trainingOptions('sgdm',...
    'Plots','training-progress',...
    'MiniBatchSize',1,...
    'CheckpointPath', st,...
    'Momentum',0.99,...
    'InitialLearnRate', 1e-12,...
  'L2Regularization',0.0005);

      [net, info] = trainNetwork(datasource,lgraph,options);
  else
      options = trainingOptions('sgdm',...
      'Plots','training-progress',...
      'MaxEpochs',19, ...
      'MiniBatchSize',1,...
      'CheckpointPath', st,...
      'Momentum',0.99,...
      'InitialLearnRate', 1e-12,...
    'L2Regularization',0.0005);
      data = load (strcat(st,filesep,'convnet_checkpoint__4607__2018_01_27__21_25_03.mat'));
      war = data.net;
      [sp, info] = trainNetwork(datasource,war.Layers,options);
  end

Answer 1

[Suvidha Tripathi]

When you are resuming training from a checkpoint in case of layer graph object, then just do this modification

newlgraph=layerGraph(net);
new_net = trainNetwork(pximds,newlgraph,options)

where net is your last checkpoint network.