Where are you located?
From what I've read (I'm trying to relocate the source), Britbox UK is being shut down as a separate service, with its content being blended into ITVX Premium. Outside UK, international versions of Britbox are continuing on their own.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X
