Segmentation in Pytorch

Hi guys,
I have been trying Image segmentation based on fast ai camvid dataset video.
I’m facing a problem like my model is not converging and sometimes my lr.learn is showing smooth graph and sometimes haphazard one, also I’m getting this weird messages which I’m not able to sort
Like once I gor lr = 1e-04 but other time I simply can’t use that lr as I got haphazard lr graph
link for code:

link for dataset:

Would really appreciate any help as couldn’t figure out what was the problem for 2 days

Thanks in Advance