diff --git a/python/core/auto_generated/symbology/qgscategorizedsymbolrenderer.sip.in b/python/core/auto_generated/symbology/qgscategorizedsymbolrenderer.sip.in
index f44dc33f675..c8a632736c9 100644
--- a/python/core/auto_generated/symbology/qgscategorizedsymbolrenderer.sip.in
+++ b/python/core/auto_generated/symbology/qgscategorizedsymbolrenderer.sip.in
@@ -336,6 +336,7 @@ the categories' color.
 .. seealso:: :py:func:`sourceColorRamp`
 %End
 
+
     void setSourceSymbol( QgsSymbol *sym /Transfer/ );
 %Docstring
 Sets the source symbol for the renderer, which is the base symbol used for the each categories' symbol before applying
@@ -357,6 +358,7 @@ Returns the source color ramp, from which each categories' color is derived.
 .. seealso:: :py:func:`sourceSymbol`
 %End
 
+
     void setSourceColorRamp( QgsColorRamp *ramp /Transfer/ );
 %Docstring
 Sets the source color ramp.
diff --git a/python/core/auto_generated/symbology/qgsgraduatedsymbolrenderer.sip.in b/python/core/auto_generated/symbology/qgsgraduatedsymbolrenderer.sip.in
index 9f9f10deebf..6ebcd571120 100644
--- a/python/core/auto_generated/symbology/qgsgraduatedsymbolrenderer.sip.in
+++ b/python/core/auto_generated/symbology/qgsgraduatedsymbolrenderer.sip.in
@@ -347,6 +347,7 @@ the classes' color.
 .. seealso:: :py:func:`sourceColorRamp`
 %End
 
+
     void setSourceSymbol( QgsSymbol *sym /Transfer/ );
 %Docstring
 Sets the source symbol for the renderer, which is the base symbol used for the each classes' symbol before applying
@@ -368,6 +369,7 @@ Returns the source color ramp, from which each classes' color is derived.
 .. seealso:: :py:func:`sourceSymbol`
 %End
 
+
     void setSourceColorRamp( QgsColorRamp *ramp /Transfer/ );
 %Docstring
 Sets the source color ramp.
diff --git a/src/core/symbology/qgscategorizedsymbolrenderer.cpp b/src/core/symbology/qgscategorizedsymbolrenderer.cpp
index 690c43e52da..5f5ec683110 100644
--- a/src/core/symbology/qgscategorizedsymbolrenderer.cpp
+++ b/src/core/symbology/qgscategorizedsymbolrenderer.cpp
@@ -20,6 +20,7 @@
 #include "qgssymbol.h"
 #include "qgssymbollayerutils.h"
 #include "qgscolorramp.h"
+#include "qgsgraduatedsymbolrenderer.h"
 #include "qgspointdisplacementrenderer.h"
 #include "qgsinvertedpolygonrenderer.h"
 #include "qgspainteffect.h"
@@ -953,6 +954,12 @@ QgsSymbol *QgsCategorizedSymbolRenderer::sourceSymbol()
 {
   return mSourceSymbol.get();
 }
+
+const QgsSymbol *QgsCategorizedSymbolRenderer::sourceSymbol() const
+{
+  return mSourceSymbol.get();
+}
+
 void QgsCategorizedSymbolRenderer::setSourceSymbol( QgsSymbol *sym )
 {
   mSourceSymbol.reset( sym );
@@ -963,6 +970,11 @@ QgsColorRamp *QgsCategorizedSymbolRenderer::sourceColorRamp()
   return mSourceColorRamp.get();
 }
 
+const QgsColorRamp *QgsCategorizedSymbolRenderer::sourceColorRamp() const
+{
+  return mSourceColorRamp.get();
+}
+
 void QgsCategorizedSymbolRenderer::setSourceColorRamp( QgsColorRamp *ramp )
 {
   mSourceColorRamp.reset( ramp );
@@ -1038,22 +1050,36 @@ void QgsCategorizedSymbolRenderer::checkLegendSymbolItem( const QString &key, bo
 
 QgsCategorizedSymbolRenderer *QgsCategorizedSymbolRenderer::convertFromRenderer( const QgsFeatureRenderer *renderer )
 {
-  QgsCategorizedSymbolRenderer *r = nullptr;
+  std::unique_ptr< QgsCategorizedSymbolRenderer > r;
   if ( renderer->type() == QLatin1String( "categorizedSymbol" ) )
   {
-    r = dynamic_cast<QgsCategorizedSymbolRenderer *>( renderer->clone() );
+    r.reset( static_cast<QgsCategorizedSymbolRenderer *>( renderer->clone() ) );
+  }
+  else if ( renderer->type() == QLatin1String( "graduatedSymbol" ) )
+  {
+    const QgsGraduatedSymbolRenderer *graduatedSymbolRenderer = dynamic_cast<const QgsGraduatedSymbolRenderer *>( renderer );
+    if ( graduatedSymbolRenderer )
+    {
+      r.reset( new QgsCategorizedSymbolRenderer( QString(), QgsCategoryList() ) );
+      r->setSourceSymbol( graduatedSymbolRenderer->sourceSymbol()->clone() );
+      if ( graduatedSymbolRenderer->sourceColorRamp() )
+      {
+        r->setSourceColorRamp( graduatedSymbolRenderer->sourceColorRamp()->clone() );
+      }
+      r->setClassAttribute( graduatedSymbolRenderer->classAttribute() );
+    }
   }
   else if ( renderer->type() == QLatin1String( "pointDisplacement" ) || renderer->type() == QLatin1String( "pointCluster" ) )
   {
     const QgsPointDistanceRenderer *pointDistanceRenderer = dynamic_cast<const QgsPointDistanceRenderer *>( renderer );
     if ( pointDistanceRenderer )
-      r = convertFromRenderer( pointDistanceRenderer->embeddedRenderer() );
+      r.reset( convertFromRenderer( pointDistanceRenderer->embeddedRenderer() ) );
   }
   else if ( renderer->type() == QLatin1String( "invertedPolygonRenderer" ) )
   {
     const QgsInvertedPolygonRenderer *invertedPolygonRenderer = dynamic_cast<const QgsInvertedPolygonRenderer *>( renderer );
     if ( invertedPolygonRenderer )
-      r = convertFromRenderer( invertedPolygonRenderer->embeddedRenderer() );
+      r.reset( convertFromRenderer( invertedPolygonRenderer->embeddedRenderer() ) );
   }
 
   // If not one of the specifically handled renderers, then just grab the symbol from the renderer
@@ -1061,7 +1087,7 @@ QgsCategorizedSymbolRenderer *QgsCategorizedSymbolRenderer::convertFromRenderer(
 
   if ( !r )
   {
-    r = new QgsCategorizedSymbolRenderer( QString(), QgsCategoryList() );
+    r = qgis::make_unique< QgsCategorizedSymbolRenderer >( QString(), QgsCategoryList() );
     QgsRenderContext context;
     QgsSymbolList symbols = const_cast<QgsFeatureRenderer *>( renderer )->symbols( context );
     if ( !symbols.isEmpty() )
@@ -1073,7 +1099,7 @@ QgsCategorizedSymbolRenderer *QgsCategorizedSymbolRenderer::convertFromRenderer(
   r->setOrderBy( renderer->orderBy() );
   r->setOrderByEnabled( renderer->orderByEnabled() );
 
-  return r;
+  return r.release();
 }
 
 void QgsCategorizedSymbolRenderer::setDataDefinedSizeLegend( QgsDataDefinedSizeLegend *settings )
diff --git a/src/core/symbology/qgscategorizedsymbolrenderer.h b/src/core/symbology/qgscategorizedsymbolrenderer.h
index 74b8bf9d1a8..ce6e287fb36 100644
--- a/src/core/symbology/qgscategorizedsymbolrenderer.h
+++ b/src/core/symbology/qgscategorizedsymbolrenderer.h
@@ -323,6 +323,15 @@ class CORE_EXPORT QgsCategorizedSymbolRenderer : public QgsFeatureRenderer
      */
     QgsSymbol *sourceSymbol();
 
+    /**
+     * Returns the renderer's source symbol, which is the base symbol used for the each categories' symbol before applying
+     * the categories' color.
+     * \see setSourceSymbol()
+     * \see sourceColorRamp()
+     * \note Not available in Python bindings.
+     */
+    const QgsSymbol *sourceSymbol() const SIP_SKIP;
+
     /**
      * Sets the source symbol for the renderer, which is the base symbol used for the each categories' symbol before applying
      * the categories' color.
@@ -339,6 +348,14 @@ class CORE_EXPORT QgsCategorizedSymbolRenderer : public QgsFeatureRenderer
      */
     QgsColorRamp *sourceColorRamp();
 
+    /**
+     * Returns the source color ramp, from which each categories' color is derived.
+     * \see setSourceColorRamp()
+     * \see sourceSymbol()
+     * \note Not available in Python bindings.
+     */
+    const QgsColorRamp *sourceColorRamp() const SIP_SKIP;
+
     /**
      * Sets the source color ramp.
       * \param ramp color ramp. Ownership is transferred to the renderer
diff --git a/src/core/symbology/qgsgraduatedsymbolrenderer.cpp b/src/core/symbology/qgsgraduatedsymbolrenderer.cpp
index 4a61fa943c6..8fd0e8df4d6 100644
--- a/src/core/symbology/qgsgraduatedsymbolrenderer.cpp
+++ b/src/core/symbology/qgsgraduatedsymbolrenderer.cpp
@@ -21,6 +21,7 @@
 #include "qgsgraduatedsymbolrenderer.h"
 
 #include "qgsattributes.h"
+#include "qgscategorizedsymbolrenderer.h"
 #include "qgscolorramp.h"
 #include "qgsdatadefinedsizelegend.h"
 #include "qgsexpression.h"
@@ -795,6 +796,12 @@ QgsSymbol *QgsGraduatedSymbolRenderer::sourceSymbol()
 {
   return mSourceSymbol.get();
 }
+
+const QgsSymbol *QgsGraduatedSymbolRenderer::sourceSymbol() const
+{
+  return mSourceSymbol.get();
+}
+
 void QgsGraduatedSymbolRenderer::setSourceSymbol( QgsSymbol *sym )
 {
   mSourceSymbol.reset( sym );
@@ -805,6 +812,11 @@ QgsColorRamp *QgsGraduatedSymbolRenderer::sourceColorRamp()
   return mSourceColorRamp.get();
 }
 
+const QgsColorRamp *QgsGraduatedSymbolRenderer::sourceColorRamp() const
+{
+  return mSourceColorRamp.get();
+}
+
 void QgsGraduatedSymbolRenderer::setSourceColorRamp( QgsColorRamp *ramp )
 {
   if ( ramp == mSourceColorRamp.get() )
@@ -1208,22 +1220,39 @@ void QgsGraduatedSymbolRenderer::setAstride( bool astride ) SIP_DEPRECATED
 
 QgsGraduatedSymbolRenderer *QgsGraduatedSymbolRenderer::convertFromRenderer( const QgsFeatureRenderer *renderer )
 {
-  QgsGraduatedSymbolRenderer *r = nullptr;
+  std::unique_ptr< QgsGraduatedSymbolRenderer > r;
   if ( renderer->type() == QLatin1String( "graduatedSymbol" ) )
   {
-    r = dynamic_cast<QgsGraduatedSymbolRenderer *>( renderer->clone() );
+    r.reset( static_cast<QgsGraduatedSymbolRenderer *>( renderer->clone() ) );
+  }
+  else if ( renderer->type() == QLatin1String( "categorizedSymbol" ) )
+  {
+    const QgsCategorizedSymbolRenderer *categorizedSymbolRenderer = dynamic_cast<const QgsCategorizedSymbolRenderer *>( renderer );
+    if ( categorizedSymbolRenderer )
+    {
+      r = qgis::make_unique< QgsGraduatedSymbolRenderer >( QString(), QgsRangeList() );
+      r->setSourceSymbol( categorizedSymbolRenderer->sourceSymbol()->clone() );
+      if ( categorizedSymbolRenderer->sourceColorRamp() )
+      {
+        bool isRandom = dynamic_cast<const QgsRandomColorRamp *>( categorizedSymbolRenderer->sourceColorRamp() ) ||
+                        dynamic_cast<const QgsLimitedRandomColorRamp *>( categorizedSymbolRenderer->sourceColorRamp() );
+        if ( !isRandom )
+          r->setSourceColorRamp( categorizedSymbolRenderer->sourceColorRamp()->clone() );
+      }
+      r->setClassAttribute( categorizedSymbolRenderer->classAttribute() );
+    }
   }
   else if ( renderer->type() == QLatin1String( "pointDisplacement" ) || renderer->type() == QLatin1String( "pointCluster" ) )
   {
     const QgsPointDistanceRenderer *pointDistanceRenderer = dynamic_cast<const QgsPointDistanceRenderer *>( renderer );
     if ( pointDistanceRenderer )
-      r = convertFromRenderer( pointDistanceRenderer->embeddedRenderer() );
+      r.reset( convertFromRenderer( pointDistanceRenderer->embeddedRenderer() ) );
   }
   else if ( renderer->type() == QLatin1String( "invertedPolygonRenderer" ) )
   {
     const QgsInvertedPolygonRenderer *invertedPolygonRenderer = dynamic_cast<const QgsInvertedPolygonRenderer *>( renderer );
     if ( invertedPolygonRenderer )
-      r = convertFromRenderer( invertedPolygonRenderer->embeddedRenderer() );
+      r.reset( convertFromRenderer( invertedPolygonRenderer->embeddedRenderer() ) );
   }
 
   // If not one of the specifically handled renderers, then just grab the symbol from the renderer
@@ -1231,7 +1260,7 @@ QgsGraduatedSymbolRenderer *QgsGraduatedSymbolRenderer::convertFromRenderer( con
 
   if ( !r )
   {
-    r = new QgsGraduatedSymbolRenderer( QString(), QgsRangeList() );
+    r = qgis::make_unique< QgsGraduatedSymbolRenderer >( QString(), QgsRangeList() );
     QgsRenderContext context;
     QgsSymbolList symbols = const_cast<QgsFeatureRenderer *>( renderer )->symbols( context );
     if ( !symbols.isEmpty() )
@@ -1243,7 +1272,7 @@ QgsGraduatedSymbolRenderer *QgsGraduatedSymbolRenderer::convertFromRenderer( con
   r->setOrderBy( renderer->orderBy() );
   r->setOrderByEnabled( renderer->orderByEnabled() );
 
-  return r;
+  return r.release();
 }
 
 void QgsGraduatedSymbolRenderer::setDataDefinedSizeLegend( QgsDataDefinedSizeLegend *settings )
diff --git a/src/core/symbology/qgsgraduatedsymbolrenderer.h b/src/core/symbology/qgsgraduatedsymbolrenderer.h
index c25019c04b0..ef1eb1160f0 100644
--- a/src/core/symbology/qgsgraduatedsymbolrenderer.h
+++ b/src/core/symbology/qgsgraduatedsymbolrenderer.h
@@ -300,6 +300,15 @@ class CORE_EXPORT QgsGraduatedSymbolRenderer : public QgsFeatureRenderer
      */
     QgsSymbol *sourceSymbol();
 
+    /**
+     * Returns the renderer's source symbol, which is the base symbol used for the each classes' symbol before applying
+     * the classes' color.
+     * \see setSourceSymbol()
+     * \see sourceColorRamp()
+     * \note Not available in Python bindings.
+     */
+    const QgsSymbol *sourceSymbol() const SIP_SKIP;
+
     /**
      * Sets the source symbol for the renderer, which is the base symbol used for the each classes' symbol before applying
      * the classes' color.
@@ -316,6 +325,14 @@ class CORE_EXPORT QgsGraduatedSymbolRenderer : public QgsFeatureRenderer
      */
     QgsColorRamp *sourceColorRamp();
 
+    /**
+     * Returns the source color ramp, from which each classes' color is derived.
+     * \see setSourceColorRamp()
+     * \see sourceSymbol()
+     * \note Not available in Python bindings.
+     */
+    const QgsColorRamp *sourceColorRamp() const SIP_SKIP;
+
     /**
      * Sets the source color ramp.
      * \param ramp color ramp. Ownership is transferred to the renderer