运行yolov5时会提示In PyTorch 1.1.0 and later, you should call them in the opposite order: `optimizer.step()` before `optimizer.step()`.CSDN有大佬讲了具体原因和操作，但没有针对ylov5 v6.2版本的修改方法。具体方法就是修改train.py

# Scheduler
lr = [x['lr'] for x in optimizer.param_groups]  # for loggers
scheduler.step()

移动scheduler.step()到下面的位置，注意与end training前面的#对齐

    # end epoch ----------------------------------------------------    
# end training ------------------------------------------------------------------------

下面就是修改后的

        # end epoch -----------------------------------------------------------------------
    scheduler.step()
    # end training ------------------------------------------------------------------------