ERPnext on frappe internal server error

I tried to use ERPNext today, and it gives me internal server error.
Later, it says Daily Usage Limit Reached.
Upon checking, I see that the usage spiked to crazy amount.

I think there must be some strange issue happening. How to fix it?

Same thing. I have unusual high CPU usage. And the site was several hours down. Though it’s up again. Would be nice to know