diff --git a/ProcessLib/RichardsComponentTransport/CreateRichardsComponentTransportProcess.cpp b/ProcessLib/RichardsComponentTransport/CreateRichardsComponentTransportProcess.cpp
index c81b5e1c9fb3b91fe324505b8ad88f5aaf52c150..d8230ee3d15236e926641e221007359079707b0d 100644
--- a/ProcessLib/RichardsComponentTransport/CreateRichardsComponentTransportProcess.cpp
+++ b/ProcessLib/RichardsComponentTransport/CreateRichardsComponentTransportProcess.cpp
@@ -65,6 +65,8 @@ std::unique_ptr<Process> createRichardsComponentTransportProcess(
     }
     else  // staggered scheme.
     {
+        OGS_FATAL("The staggered coupling scheme is not implemented.");
+
         using namespace std::string_literals;
         for (auto const& variable_name : {"concentration"s, "pressure"s})
         {