Hey Kathleen,
I removed the site password you posted for security reasons. We have not logged into your site and unfortunately cannot log into customer sites for any reason – your willingness to share that in the name of troubleshooting your site’s problems is much appreciated though!
There are two pieces of bad news here:
1. Yes, this does seem to be stemming from your theme. The fact that things worked fine in Twenty Fifteen almost guarantees this to be the case.
2. We unfortunately cannot offer support for third-party plugins or themes here. I’m sorry about this! But your best course of action is to contact the theme developer directly for theme support, or to just outright google the exact error you get and see if you can find a common cause – and solution – for this error online.
Sorry to disappoint here Kathleen. Please let me know if there’s anything else I can help with!
— George