diff --git a/compiler/cpp/src/thrift/generate/t_csharp_generator.cc b/compiler/cpp/src/thrift/generate/t_csharp_generator.cc
index e4d99b2..a6ece80 100644
--- a/compiler/cpp/src/thrift/generate/t_csharp_generator.cc
+++ b/compiler/cpp/src/thrift/generate/t_csharp_generator.cc
@@ -87,6 +87,8 @@
       }
     }
 
+    pwarning(1, "The 'csharp' target is deprecated. Consider using 'netstd' instead.\n");
+
     out_dir_base_ = "gen-csharp";
   }
   void init_generator() override;
diff --git a/compiler/cpp/src/thrift/generate/t_netcore_generator.cc b/compiler/cpp/src/thrift/generate/t_netcore_generator.cc
index 1a5c384..ed6a365 100644
--- a/compiler/cpp/src/thrift/generate/t_netcore_generator.cc
+++ b/compiler/cpp/src/thrift/generate/t_netcore_generator.cc
@@ -91,6 +91,8 @@
         }
     }
 
+    pwarning(1, "The 'netcore' target is deprecated. Consider using 'netstd' instead.\n");
+
     out_dir_base_ = "gen-netcore";
 }
 
diff --git a/compiler/cpp/src/thrift/parse/t_program.h b/compiler/cpp/src/thrift/parse/t_program.h
index 140dc35..e0b4b6e 100644
--- a/compiler/cpp/src/thrift/parse/t_program.h
+++ b/compiler/cpp/src/thrift/parse/t_program.h
@@ -291,6 +291,10 @@
         pwarning(1, "Namespace 'smalltalk' is deprecated. Use 'st' instead");
         base_language = "st";
       }
+      else if ((base_language == "csharp") || (base_language == "netcore")) {
+        pwarning(1, "The '%s' target is deprecated. Consider moving to 'netstd' instead.", base_language.c_str());
+        // warn only, don't change base_language
+      }
 
       t_generator_registry::gen_map_t my_copy = t_generator_registry::get_generator_map();