Hi,
I had the same error that I think has been fixed.
In the end it seems like the number of epochs you had mentioned in your scheduler was less than the number of epochs you tried training for.
I went into %debug in the notebook and tried calling self.get_lr() as suggested.
I got this message:
*** ValueError: Tried to step 3752 times. The specified number of total steps is 3750
Then with some basic math and a lot of code search I realised that I had specified 5 epochs in my scheduler but called for 10 epochs in my fit function.
Hope this helps.