Hi Carla,
It looks like the time-series object is failing to find any valid datasets. You can test this by removing the call to the RockstarHaloFinder and doing this after es.get_time_series:
for ds in es:
print (ds)
I'm guessing that will not print anything. I imagine you'll just need to put the find_outputs=True back, but if that's not the case, then something has changed about the way the datasets are being named such that the EnzoSimulation can't find anything of the names it expects.
Once you get that fixed, I think the other issue you'll encounter is that Rockstar will be confused about which dataset on which to resume. You'll need to make sure that the datasets.txt file has all the previous datasets in it. I think the only way to accomplish this is to replace the original dataset directories and just put the dataset parameter files inside them.
Britton