Improve assert p:f:T::create_triangulation()

diff --git a/source/distributed/fully_distributed_tria.cc b/source/distributed/fully_distributed_tria.cc
index 6bee001262bff8f55e5eed30e4d1f6581a82b8c9..774ab21328ee0240f7dc548b6fcd688482177310 100644 (file)
--- a/source/distributed/fully_distributed_tria.cc
+++ b/source/distributed/fully_distributed_tria.cc
@@ -217,10 +217,20 @@ namespace parallel
       const std::vector<dealii::CellData<dim>> &cells,
       const SubCellData &                       subcelldata)
     {
-      AssertThrow(
+      Assert(
         currently_processing_create_triangulation_for_internal_usage,
         ExcMessage(
-          "Use the other create_triangulation() function to create triangulations of type parallel::fullydistributed::Triangulation.!"));
+          "You have called the method parallel::fullydistributed::Triangulation::create_triangulation() \n"
+          "that takes 3 arguments. If you have not called this function directly, \n"
+          "it might have been called via a function from the GridGenerator or GridIn \n"
+          "namespace. To be able to setup a fully-distributed Triangulation with these \n"
+          "utility functions nevertheless, please follow the following three steps:\n"
+          "  1) call the utility function for a (serial) Triangulation, \n"
+          "     a parallel::shared::Triangulation, or a parallel::distributed::Triangulation object,\n"
+          "  2) use the functions TriangulationDescription::Utilities::create_description_from_triangulation() \n"
+          "     or ::create_description_from_triangulation_in_groups() to create the \n"
+          "     description of the local partition, and\n"
+          "  3) pass the created description to parallel::fullydistributed::Triangulation::create_triangulation()."));
 
       dealii::Triangulation<dim, spacedim>::create_triangulation(vertices,
                                                                  cells,