Thanks so much for reaching out!
As a first step, can you update all of your Events Calendar related plugins to their most recent versions and see if you still get the error?
In addition, can you provide me with the URL that you are trying to import, so that I can do some testing on my end?
Also, can you enable and check the Event Log under Events < Help to see if you see anything unusual?
Right under that is your Event Aggregator Status. Can you take a screenshot of what you see there?
Let me know if you have any other questions in the meantime!
Thanks,
Jaime