From TfL's live travel news / 'service update now' page:

---quote---
DALSTON JUNCTION TO WEST CROYDON Suspended between Sydenham and West
Croydon due to a faulty train at Anerly. Severe delays are occurring
on the rest of the line.
---/quote---

I await news of vegetation blocking the line at Broccoli, delays at
Whopping due to overcrowding, and services suspended because of
passenger action at Shagwell.