Index: magnolia-core/src/main/java/info/magnolia/freemarker/ModeDependentTemplateExceptionHandler.java
===================================================================
--- magnolia-core/src/main/java/info/magnolia/freemarker/ModeDependentTemplateExceptionHandler.java	(revision )
+++ magnolia-core/src/main/java/info/magnolia/freemarker/ModeDependentTemplateExceptionHandler.java	(revision )
@@ -0,0 +1,35 @@
+package info.magnolia.freemarker;
+
+import freemarker.core.Environment;
+import freemarker.template.TemplateException;
+import freemarker.template.TemplateExceptionHandler;
+import info.magnolia.cms.beans.config.ServerConfiguration;
+import info.magnolia.context.MgnlContext;
+
+import java.io.Writer;
+
+/**
+ *
+ * @author gjoseph
+ * @version $Revision: $ ($Author: $)
+ */
+public class ModeDependentTemplateExceptionHandler implements TemplateExceptionHandler {
+    public void handleTemplateException(TemplateException te, Environment env, Writer out) throws TemplateException {
+        final boolean isAuthorInstance = ServerConfiguration.getInstance().isAdmin();
+        final boolean isPreviewMode = MgnlContext.getAggregationState().isPreviewMode();
+        if (isAuthorInstance && !isPreviewMode) {
+            inEditMode(te, env, out);
+        } else {
+            inPublicMode(te, env, out);
+        }
+
+    }
+
+    protected void inPublicMode(TemplateException te, Environment env, Writer out) throws TemplateException {
+        TemplateExceptionHandler.IGNORE_HANDLER.handleTemplateException(te, env, out);
+    }
+
+    protected void inEditMode(TemplateException te, Environment env, Writer out) throws TemplateException {
+        TemplateExceptionHandler.HTML_DEBUG_HANDLER.handleTemplateException(te, env, out);
+    }
+}
Index: magnolia-core/src/main/java/info/magnolia/freemarker/FreemarkerHelper.java
===================================================================
--- magnolia-core/src/main/java/info/magnolia/freemarker/FreemarkerHelper.java	(revision 32667)
+++ magnolia-core/src/main/java/info/magnolia/freemarker/FreemarkerHelper.java	(revision )
@@ -105,6 +105,7 @@
                 return value;
             }
         };
+        cfg.setTemplateExceptionHandler(freemarkerConfig.getTemplateExceptionHandler());
 
         // ... and here we essentially do the same by instantiate delegator implementations of FreeMarker components, which delegate to our observed FreemarkerConfig
         // these setters do more than their equivalent getters, so we can't just override the getter instead.
@@ -112,11 +113,8 @@
         cfg.setTemplateLoader(new ConfigDelegatingTemplateLoader(freemarkerConfig));
         cfg.setObjectWrapper(new ConfigDelegatingObjectWrapper(freemarkerConfig));
 
-
         cfg.setTagSyntax(Configuration.AUTO_DETECT_TAG_SYNTAX);
         cfg.setDefaultEncoding("UTF8");
-        // TODO : configure this (maybe based on the dev-mode system property)
-        cfg.setTemplateExceptionHandler(TemplateExceptionHandler.HTML_DEBUG_HANDLER);
         //cfg.setTemplateUpdateDelay(10);
     }
 
Index: magnolia-core/src/main/java/info/magnolia/freemarker/FreemarkerConfig.java
===================================================================
--- magnolia-core/src/main/java/info/magnolia/freemarker/FreemarkerConfig.java	(revision 34144)
+++ magnolia-core/src/main/java/info/magnolia/freemarker/FreemarkerConfig.java	(revision )
@@ -37,6 +37,7 @@
 import freemarker.cache.MultiTemplateLoader;
 import freemarker.cache.TemplateLoader;
 import freemarker.template.ObjectWrapper;
+import freemarker.template.TemplateExceptionHandler;
 import freemarker.template.TemplateModel;
 import freemarker.template.TemplateModelException;
 import info.magnolia.freemarker.models.MagnoliaModelFactory;
@@ -73,6 +74,7 @@
     private final List<MagnoliaModelFactory> registeredModelFactories;
     private final List<TemplateLoader> templateLoaders;
     private final Map<String, TemplateModel> sharedVariables;
+    private TemplateExceptionHandler templateExceptionHandler = new ModeDependentTemplateExceptionHandler();
 
     private ObjectWrapper objectWrapper;
     private TemplateLoader multiTL;
@@ -134,4 +136,12 @@
     public void addSharedVariable(String name, TemplateModel value) {
         sharedVariables.put(name, value);
     }
+
+    public TemplateExceptionHandler getTemplateExceptionHandler() {
+        return templateExceptionHandler;
-}
+    }
+
+    public void setTemplateExceptionHandler(TemplateExceptionHandler templateExceptionHandler) {
+        this.templateExceptionHandler = templateExceptionHandler;
+    }
+}