I was editing a node of mine and this error came across (as seen in the attachment below). However, while editing other nodes, the error does not happen only that node. I deleted the node and created one under the same name and the error still persisted. This hasn't happened before at all and haven't touched any add-ons in the last 24 hours and haven't touched much in the AdminCP beyond editing page. It's only happened now, so I'm really confused about what is happening.
This is the AdminCP: