diff --git a/src/solver/newton_raphson.jl b/src/solver/newton_raphson.jl
index 36991db0c..08f6754aa 100644
--- a/src/solver/newton_raphson.jl
+++ b/src/solver/newton_raphson.jl
@@ -108,6 +108,7 @@ function setup_solver_caches(coupled_problem::CoupledProblem{<:Tuple{<:QuasiStat
         face_caches,
         dh,
     )
+    error("Not implemented yet")
     # TODO introduce CouplingOperator
     # BlockOperator((
     #     quasi_static_operator, NullOperator{Float64,1,ndofs(dh)}(),