We planned a route on Komoot from Sampford Courtenay to Tiverton. The route took us down an impassable path at the end of Valscombe Lane. It was signposted as an unregistered byway. Initially it was like a bridle way and became very muddy. Then the mud turned to rocks and stones. No way could you ride a e bike or mountain bike. It was treacherous to guide the bikes and walking was virtually impossible too. I believe it is a run off from the local river. The path was very steep. 
When we eventually  came out onto a road, we met a local who lives on this lane. He informed us that cyclists were regularly sent down this path by sat nav’s and they shouldn’t be. Local people do not use this path as it is dangerous. 