diff --git a/CHANGELOG.md b/CHANGELOG.md
index 07219bfc..ae2be02b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -40,6 +40,10 @@ RELEASING:
 14. Create new release in GitHub with tag version and release title of `vX.X.X`
  -->
 
+## Unreleased
+### Fixed
+- Log the correct ApiError message in the isochrone processing algorithm with > 10 ranges ([#264](https://github.com/GIScience/orstools-qgis-plugin/issues/264))
+
 ## [1.8.4] - 2024-07-29
 
 ### Fixed
diff --git a/ORStools/common/isochrones_core.py b/ORStools/common/isochrones_core.py
index 57efaea0..fe36d92d 100644
--- a/ORStools/common/isochrones_core.py
+++ b/ORStools/common/isochrones_core.py
@@ -29,21 +29,19 @@
 
 from typing import Any, Generator
 
-from qgis._core import QgsMapLayer
 from qgis.core import (
     QgsPointXY,
     QgsFeature,
     QgsField,
     QgsFields,
     QgsGeometry,
-    QgsSymbol,
-    QgsSimpleFillSymbolLayer,
-    QgsRendererCategory,
-    QgsCategorizedSymbolRenderer,
+    QgsGraduatedSymbolRenderer,
+    QgsMapLayer,
+    QgsStyle,
+    QgsClassificationEqualInterval,
 )
 
 from qgis.PyQt.QtCore import QVariant
-from qgis.PyQt.QtGui import QColor
 
 
 # import processing
@@ -176,49 +174,20 @@ def stylePoly(self, layer: QgsMapLayer) -> None:
         :type layer: QgsMapLayer
         """
 
-        if self.dimension == "time":
-            legend_suffix = " min"
-        else:
-            legend_suffix = " m"
-
         field = layer.fields().indexOf(self.field_dimension_name)
         unique_values = sorted(layer.uniqueValues(field))
 
-        colors = {
-            0: QColor("#2b83ba"),
-            1: QColor("#64abb0"),
-            2: QColor("#9dd3a7"),
-            3: QColor("#c7e9ad"),
-            4: QColor("#edf8b9"),
-            5: QColor("#ffedaa"),
-            6: QColor("#fec980"),
-            7: QColor("#f99e59"),
-            8: QColor("#e85b3a"),
-            9: QColor("#d7191c"),
-        }
-
-        categories = []
-
-        for cid, unique_value in enumerate(unique_values):
-            # initialize the default symbol for this geometry type
-            symbol = QgsSymbol.defaultSymbol(layer.geometryType())
-
-            # configure a symbol layer
-            symbol_layer = QgsSimpleFillSymbolLayer(
-                color=colors[cid], strokeColor=QColor("#000000")
-            )
-
-            # replace default symbol layer with the configured one
-            if symbol_layer is not None:
-                symbol.changeSymbolLayer(0, symbol_layer)
-
-            # create renderer object
-            category = QgsRendererCategory(unique_value, symbol, str(unique_value) + legend_suffix)
-            # entry for the list of category items
-            categories.append(category)
-
-        # create renderer object
-        renderer = QgsCategorizedSymbolRenderer(self.field_dimension_name, categories)
+        classification_method = QgsClassificationEqualInterval()
+        ramp_name = "Spectral"
+        default_style = QgsStyle().defaultStyle()
+        color_ramp = default_style.colorRamp(ramp_name)
+        color_ramp.invert()
+        num_classes = len(unique_values)
+
+        renderer = QgsGraduatedSymbolRenderer(self.field_dimension_name)
+        renderer.setSourceColorRamp(color_ramp)
+        renderer.setClassificationMethod(classification_method)
+        renderer.updateClasses(layer, num_classes)
 
         # assign the created renderer to the layer
         if renderer is not None: