diff --git a/src/db/db/dbLayerProperties.h b/src/db/db/dbLayerProperties.h
index 8875228f0..43a4c813f 100644
--- a/src/db/db/dbLayerProperties.h
+++ b/src/db/db/dbLayerProperties.h
@@ -229,5 +229,17 @@ inline LayerProperties &operator+= (LayerProperties &props, const LayerOffset &o
 
 }
 
+/**
+ *  @brief Special extractors for LayerProperties and LayerOffset
+ */
+namespace tl
+{
+  template<> DB_PUBLIC void extractor_impl<db::LayerProperties> (tl::Extractor &ex, db::LayerProperties &p);
+  template<> DB_PUBLIC void extractor_impl<db::LayerOffset> (tl::Extractor &ex, db::LayerOffset &p);
+
+  template<> DB_PUBLIC bool test_extractor_impl<db::LayerProperties> (tl::Extractor &ex, db::LayerProperties &p);
+  template<> DB_PUBLIC bool test_extractor_impl<db::LayerOffset> (tl::Extractor &ex, db::LayerOffset &p);
+} // namespace tl
+
 #endif
 
diff --git a/src/db/db/dbTrans.h b/src/db/db/dbTrans.h
index 115f6b920..f20438b6e 100644
--- a/src/db/db/dbTrans.h
+++ b/src/db/db/dbTrans.h
@@ -2671,6 +2671,7 @@ namespace tl
   template<> DB_PUBLIC void extractor_impl (tl::Extractor &ex, db::CplxTrans &t);
   template<> DB_PUBLIC void extractor_impl (tl::Extractor &ex, db::VCplxTrans &t);
   template<> DB_PUBLIC void extractor_impl (tl::Extractor &ex, db::DCplxTrans &t);
+  template<> DB_PUBLIC void extractor_impl (tl::Extractor &ex, db::ICplxTrans &t);
 
   template<> DB_PUBLIC bool test_extractor_impl (tl::Extractor &ex, db::UnitTrans &t);
   template<> DB_PUBLIC bool test_extractor_impl (tl::Extractor &ex, db::DUnitTrans &t);
@@ -2683,6 +2684,7 @@ namespace tl
   template<> DB_PUBLIC bool test_extractor_impl (tl::Extractor &ex, db::CplxTrans &t);
   template<> DB_PUBLIC bool test_extractor_impl (tl::Extractor &ex, db::VCplxTrans &t);
   template<> DB_PUBLIC bool test_extractor_impl (tl::Extractor &ex, db::DCplxTrans &t);
+  template<> DB_PUBLIC bool test_extractor_impl (tl::Extractor &ex, db::ICplxTrans &t);
 
 } // namespace tl
 
diff --git a/src/tl/tl/tlString.cc b/src/tl/tl/tlString.cc
index 833794a55..25ceef153 100644
--- a/src/tl/tl/tlString.cc
+++ b/src/tl/tl/tlString.cc
@@ -44,14 +44,14 @@ static std::locale c_locale ("C");
 // -------------------------------------------------------------------------
 //  Exception classes
 
-ExtractorNotImplementedException::ExtractorNotImplementedException ()
-  : Exception (tl::to_string (tr ("No string extractor available")))
+ExtractorNotImplementedException::ExtractorNotImplementedException (const std::type_info &ti)
+  : Exception (tl::to_string (tr ("No string extractor available for type: ")) + ti.name ())
 {
   //  .. nothing yet ..
 }
 
-StringConversionException::StringConversionException ()
-  : Exception (tl::to_string (tr ("No string conversion available")))
+StringConversionException::StringConversionException (const std::type_info &ti)
+  : Exception (tl::to_string (tr ("No string conversion available for type: ")) + ti.name ())
 {
   //  .. nothing yet ..
 }
diff --git a/src/tl/tl/tlString.h b/src/tl/tl/tlString.h
index 6266bbb04..02becf0d5 100644
--- a/src/tl/tl/tlString.h
+++ b/src/tl/tl/tlString.h
@@ -27,6 +27,7 @@
 #include "tlCommon.h"
 
 #include <string>
+#include <typeinfo>
 #include <stdexcept>
 #include <stdint.h>
 #include <stdarg.h>
@@ -48,7 +49,7 @@ class TL_PUBLIC ExtractorNotImplementedException
   : public tl::Exception
 {
 public:
-  ExtractorNotImplementedException ();
+  ExtractorNotImplementedException (const std::type_info &ti);
 };
 
 /**
@@ -58,12 +59,12 @@ class TL_PUBLIC StringConversionException
   : public tl::Exception
 {
 public:
-  StringConversionException ();
+  StringConversionException (const std::type_info &ti);
 };
 
 class Extractor;
-template <class T> void extractor_impl (tl::Extractor &, T &) { throw ExtractorNotImplementedException (); }
-template <class T> bool test_extractor_impl (tl::Extractor &, T &) { throw ExtractorNotImplementedException (); }
+template <class T> void extractor_impl (tl::Extractor &, T &) { throw ExtractorNotImplementedException (typeid (T)); }
+template <class T> bool test_extractor_impl (tl::Extractor &, T &) { throw ExtractorNotImplementedException (typeid (T)); }
 
 /**
  *  @brief Another string class
@@ -289,7 +290,7 @@ TL_PUBLIC std::string to_local (const std::string &s);
 
 template <class T, bool> struct __redirect_to_string;
 template <class T> struct __redirect_to_string<T, true> { static std::string to_string (const T &t) { return t.to_string (); } };
-template <class T> struct __redirect_to_string<T, false> { static std::string to_string  (const T &) { throw StringConversionException (); } };
+template <class T> struct __redirect_to_string<T, false> { static std::string to_string  (const T &) { throw StringConversionException (typeid (T)); } };
 template <class T> inline std::string to_string (const T &o) { return __redirect_to_string<T, tl::has_to_string<T>::value>::to_string (o); }
 
 template <> inline std::string to_string (const double &d) { return to_string (d, 12); }
diff --git a/src/tl/tl/tlVariant.h b/src/tl/tl/tlVariant.h
index 960566844..f621d4f73 100644
--- a/src/tl/tl/tlVariant.h
+++ b/src/tl/tl/tlVariant.h
@@ -55,6 +55,8 @@ namespace tl
 
 class Extractor;
 class EvalClass;
+template <class T> void extractor_impl (tl::Extractor &, T &);
+template <class T> bool test_extractor_impl (tl::Extractor &, T &);
 
 /**
  *  @brief A base class which describes a class, i.e. an object capable of converting and handling void *
@@ -1662,6 +1664,12 @@ template<> inline bool Variant::can_convert_to<const char *> () const         {
  */
 void initialize_variant_class_table ();
 
+/**
+ *  @brief Special extractors for Variant
+ */
+template<> TL_PUBLIC void extractor_impl<Variant> (tl::Extractor &ex, Variant &v);
+template<> TL_PUBLIC bool test_extractor_impl<Variant> (tl::Extractor &ex, Variant &v);
+
 } // namespace tl
 
 #endif