diff --git a/source/java/org/alfresco/repo/audit/access/NodeChange.java b/source/java/org/alfresco/repo/audit/access/NodeChange.java
index d8dacb12f3..010c588b19 100644
--- a/source/java/org/alfresco/repo/audit/access/NodeChange.java
+++ b/source/java/org/alfresco/repo/audit/access/NodeChange.java
@@ -126,6 +126,7 @@ import org.alfresco.service.namespace.QName;
     private NodeInfo nodeInfo;
 
     private String action;
+    private String runAsUser;
     
     private boolean auditSubActions = false;
     private Set<String> subActions = new LinkedHashSet<String>();
@@ -157,6 +158,8 @@ import org.alfresco.service.namespace.QName;
     {
         // Derive higher level action
         String action;
+        boolean keepRunAsUser = false;
+        
         if (subActions.contains(CHECK_OUT))
         {
             action = "CHECK OUT";
@@ -181,6 +184,8 @@ import org.alfresco.service.namespace.QName;
         {
             // Reads in combinations with other actions tend to only facilitate the other action.
             action = "READ";
+            // MNT-8810 fix, action is considered as READ -> so let's keep actual user who performed readContent 
+            keepRunAsUser = true;
         }
         else if (subActions.contains(DELETE_NODE))
         {
@@ -203,7 +208,10 @@ import org.alfresco.service.namespace.QName;
             // Default to first sub-action
             action = this.action;
         }
-            
+        if (!keepRunAsUser)
+        {
+            runAsUser = null;
+        }
         return action;
     }
     
@@ -455,6 +463,8 @@ import org.alfresco.service.namespace.QName;
     {
         appendSubAction(new NodeChange(nodeInfoFactory, namespaceService, nodeRef).
                 setAction(READ_CONTENT));
+        // MNT-8810 fix, remember runAsUser for read operation
+        runAsUser = AuthenticationUtil.getRunAsUser();
     }
 
     @Override
@@ -524,7 +534,9 @@ import org.alfresco.service.namespace.QName;
         
         if (!subAction) // no need to repeat for sub actions
         {
-            auditMap.put(USER, AuthenticationUtil.getFullyAuthenticatedUser());
+            // MNT-8810 fix, if runAsUser is not null this means that this is READ action and we should use real user who performed readContent,
+            // not the current user as actual read may be executed in runAs block (for example for thumbnail creation)
+            auditMap.put(USER, (runAsUser == null ? AuthenticationUtil.getFullyAuthenticatedUser() : runAsUser));
             addSubActionsToAuditMap(auditMap);
         
             auditMap.put(NODE, nodeInfo.getNodeRef());
diff --git a/source/java/org/alfresco/repo/jscript/ScriptNode.java b/source/java/org/alfresco/repo/jscript/ScriptNode.java
index 5d8fd93605..ba08ce872d 100644
--- a/source/java/org/alfresco/repo/jscript/ScriptNode.java
+++ b/source/java/org/alfresco/repo/jscript/ScriptNode.java
@@ -2917,8 +2917,7 @@ public class ScriptNode implements Scopeable, NamespacePrefixResolverProvider
             String nodeMimeType = getMimetype();
             Serializable value = this.nodeService.getProperty(nodeRef, ContentModel.PROP_CONTENT);
             ContentData contentData = DefaultTypeConverter.INSTANCE.convert(ContentData.class, value);
-            if (!ContentData.hasContent(contentData) ||
-                !services.getContentService().getReader(nodeRef, ContentModel.PROP_CONTENT).exists())
+            if (!ContentData.hasContent(contentData))
             {
                 if (logger.isDebugEnabled())
                     logger.debug("Unable to create thumbnail '" + details.getName() + "' as there is no content");
@@ -3023,16 +3022,17 @@ public class ScriptNode implements Scopeable, NamespacePrefixResolverProvider
      */
     public String[] getThumbnailDefinitions()
     {
-        ContentService contentService = this.services.getContentService();
         ThumbnailService thumbnailService = this.services.getThumbnailService();
         
         List<String> result = new ArrayList<String>(7);
         
-        ContentReader contentReader = contentService.getReader(this.nodeRef, ContentModel.PROP_CONTENT);
-        if (contentReader != null)
+        Serializable value = this.nodeService.getProperty(nodeRef, ContentModel.PROP_CONTENT);
+        ContentData contentData = DefaultTypeConverter.INSTANCE.convert(ContentData.class, value);
+        
+        if (ContentData.hasContent(contentData))
         {
-            String mimetype = contentReader.getMimetype();
-            List<ThumbnailDefinition> thumbnailDefinitions = thumbnailService.getThumbnailRegistry().getThumbnailDefinitions(mimetype, contentReader.getSize());
+            String mimetype = contentData.getMimetype();
+            List<ThumbnailDefinition> thumbnailDefinitions = thumbnailService.getThumbnailRegistry().getThumbnailDefinitions(mimetype, contentData.getSize());
             for (ThumbnailDefinition thumbnailDefinition : thumbnailDefinitions)
             {
                 result.add(thumbnailDefinition.getName());
diff --git a/source/java/org/alfresco/repo/rendition/executer/AbstractRenderingEngine.java b/source/java/org/alfresco/repo/rendition/executer/AbstractRenderingEngine.java
index cde75f0473..5ebe8fac50 100644
--- a/source/java/org/alfresco/repo/rendition/executer/AbstractRenderingEngine.java
+++ b/source/java/org/alfresco/repo/rendition/executer/AbstractRenderingEngine.java
@@ -36,6 +36,7 @@ import org.alfresco.model.RenditionModel;
 import org.alfresco.repo.action.ParameterDefinitionImpl;
 import org.alfresco.repo.action.executer.ActionExecuterAbstractBase;
 import org.alfresco.repo.content.MimetypeMap;
+import org.alfresco.repo.content.transform.UnimportantTransformException;
 import org.alfresco.repo.nodelocator.NodeLocator;
 import org.alfresco.repo.nodelocator.SelfNodeLocator;
 import org.alfresco.repo.policy.BehaviourFilter;
@@ -830,7 +831,7 @@ public abstract class AbstractRenderingEngine extends ActionExecuterAbstractBase
             ContentReader contentReader = contentService.getReader(sourceNode, srcContentProp);
             if (contentReader == null || !contentReader.exists())
             {
-                throw new RenditionServiceException(CONTENT_READER_NOT_FOUND_MESSAGE);
+                throw new UnimportantTransformException(CONTENT_READER_NOT_FOUND_MESSAGE);
             }
             return contentReader;
         }
diff --git a/source/test-java/org/alfresco/repo/rendition/RenditionServiceIntegrationTest.java b/source/test-java/org/alfresco/repo/rendition/RenditionServiceIntegrationTest.java
index 1ac5e9f159..90f34a9758 100644
--- a/source/test-java/org/alfresco/repo/rendition/RenditionServiceIntegrationTest.java
+++ b/source/test-java/org/alfresco/repo/rendition/RenditionServiceIntegrationTest.java
@@ -42,6 +42,7 @@ import org.alfresco.repo.content.MimetypeMap;
 import org.alfresco.repo.content.transform.AbstractContentTransformerTest;
 import org.alfresco.repo.content.transform.ContentTransformer;
 import org.alfresco.repo.content.transform.ContentTransformerRegistry;
+import org.alfresco.repo.content.transform.UnimportantTransformException;
 import org.alfresco.repo.content.transform.magick.ImageTransformationOptions;
 import org.alfresco.repo.jscript.ClasspathScriptLocation;
 import org.alfresco.repo.model.Repository;
@@ -1237,7 +1238,7 @@ public class RenditionServiceIntegrationTest extends BaseAlfrescoSpringTest
         performAsyncRendition(testTargetFolder, callback, latch, results);
         
         assertNull(results.getAssoc());
-        assertEquals("Expected a RenditionServiceException", RenditionCancelledException.class, results.getThrowable().getClass());
+        assertEquals("Expected a UnimportantTransformException", UnimportantTransformException.class, results.getThrowable().getClass());
     }
 
     /**