Better way to do multiple try/except in Python
Firstly, consider whether these shouldn't be None, but instead should be empty lists. Most of the time None is better replaced by something else like an empty list.

If that's not an option, you can use a list:

for item in [self.download_links, self.case_name...]:
    if item is not None:
         length.append( len(item) )


or a function

def add_length(obj):
   if obj is not None:
            lengths.append(len(obj))

add_length(self.download_links)
add_length(self.case_name)
...