Hank here from Shopify.
Would it be possible to share your store URL, and to confirm what theme you are using? If you are unsure of how to locate which team you have, and to find out who supports it, you can do so as per this guide.
That message normally means that there is a file missing, or perhaps an error in the name like a typo, for example. Was anything recently added to the store like an app or did you have a third-party developer working on the site? Or did you make any changes to the code?
Let me know, and I'll happily assist you further.
All the best,