I'm experiencing this error on my site quite often:
Exception #0 (Magento\Framework\Exception\NoSuchEntityException): No such entity with cartId =
It's not using multiple stores, so the entity_ids are not an issue as stated in many other solutions I have tried.
Need this error fixed, can't find anything helpful anywhere else.
Best Answer
I see a lot of people are having issues with this. It also seems there might be quite a lot of different causes. I would like to share mine in case someone else is pulling out their hair (like I did).
In my case the firefox plugin uMatrix was causing the issue.
I described it here https://github.com/magento/magento2/issues/5847#issuecomment-496153411