## *Otiluke's Resilient Sphere* blocks the ghost's ethereal travel

*Any* wall of magical force exists in and blocks movement in both the plane it exists on *and* the corresponding border ethereal, as described in the DMG's section on the [Border Ethereal](https://www.dndbeyond.com/sources/dmg/creating-a-multiverse#BorderEthereal) (emphasis added):

> A traveler on the Ethereal Plane is invisible and utterly silent to someone on the overlapped plane, and solid objects on the overlapped plane don’t hamper the movement of a creature in the Border Ethereal. The exceptions are certain magical effects **(including anything made of magical force)** and living beings.

*Otiluke's Resilient Sphere*, which is a magic spell, creates "a sphere of shimmering force", which means the sphere's barrier is made of magical force that blocks ethereal travel. Hence, even if the ghost goes into the Ethereal Plane, it is still unable to enter the sphere (or escape it, if is trapped inside).