diff --git a/engines/base/src/main/java/org/alfresco/transform/base/transform/ProcessHandler.java b/engines/base/src/main/java/org/alfresco/transform/base/transform/ProcessHandler.java
index bf2bfd56..91ed0d63 100644
--- a/engines/base/src/main/java/org/alfresco/transform/base/transform/ProcessHandler.java
+++ b/engines/base/src/main/java/org/alfresco/transform/base/transform/ProcessHandler.java
@@ -195,9 +195,12 @@ abstract class ProcessHandler extends FragmentHandler
         if (transformerName == null)
         {
             throw new TransformException(BAD_REQUEST, "No transforms for: "+
-                sourceMimetype+" -> "+targetMimetype+transformOptions.entrySet().stream()
-                .map(entry -> entry.getKey()+"="+entry.getValue())
-                .collect(Collectors.joining(", ", " ", "")));
+                sourceMimetype+
+                (sourceSizeInBytes >= 0 ? " ("+TransformerDebug.fileSize(sourceSizeInBytes)+")" : "")+
+                 " -> "+targetMimetype+
+                transformOptions.entrySet().stream()
+                    .map(entry -> entry.getKey()+"="+entry.getValue())
+                    .collect(Collectors.joining(", ", " ", "")));
         }
         return transformerName;
     }
diff --git a/engines/base/src/test/java/org/alfresco/transform/base/TransformControllerTest.java b/engines/base/src/test/java/org/alfresco/transform/base/TransformControllerTest.java
index fad89bce..bde11f48 100644
--- a/engines/base/src/test/java/org/alfresco/transform/base/TransformControllerTest.java
+++ b/engines/base/src/test/java/org/alfresco/transform/base/TransformControllerTest.java
@@ -477,6 +477,6 @@ public class TransformControllerTest
                .param("unknown", "1"))
                .andExpect(status().isBadRequest())
                .andExpect(content().string(containsString("TwoCustomTransformers Error Page")))
-               .andExpect(content().string(containsString("No transforms for:")));
+               .andExpect(content().string(containsString("No transforms for: text/plain (5 bytes) -> application/pdf unknown=1")));
     }
 }
diff --git a/model/src/main/java/org/alfresco/transform/common/TransformerDebug.java b/model/src/main/java/org/alfresco/transform/common/TransformerDebug.java
index 8ba54df6..06c3e395 100644
--- a/model/src/main/java/org/alfresco/transform/common/TransformerDebug.java
+++ b/model/src/main/java/org/alfresco/transform/common/TransformerDebug.java
@@ -322,7 +322,7 @@ public class TransformerDebug
         return String.format("%,d ms", time);
     }
 
-    private String fileSize(long size)
+    public static String fileSize(long size)
     {
         if (size < 0)
         {
@@ -346,7 +346,7 @@ public class TransformerDebug
         return fileSizeFormat(size, divider, units[units.length-1]);
     }
 
-    private String fileSizeFormat(long size, long divider, String unit)
+    private static String fileSizeFormat(long size, long divider, String unit)
     {
         size = size * 10 / divider;
         int decimalPoint = (int) size % 10;