diff --git a/li.strolch.agent/src/main/java/li/strolch/agent/impl/CachedElementMap.java b/li.strolch.agent/src/main/java/li/strolch/agent/impl/CachedElementMap.java
index f35c4db75..20b1f04e0 100644
--- a/li.strolch.agent/src/main/java/li/strolch/agent/impl/CachedElementMap.java
+++ b/li.strolch.agent/src/main/java/li/strolch/agent/impl/CachedElementMap.java
@@ -185,7 +185,7 @@ public abstract class CachedElementMap<T extends StrolchRootElement> extends Tra
 			throws StrolchException {
 		T t = getDbDao(tx).queryBy(type, id, version);
 		if (assertExists && t == null) {
-			String msg = "The element with type {0} and id {1} and version {2} does not exist!"; //$NON-NLS-1$
+			String msg = "The element with type '{0}' and id '{1}' and version '{2}' does not exist!"; //$NON-NLS-1$
 			msg = MessageFormat.format(msg, type, id, version);
 			throw new StrolchException(msg);
 		}
diff --git a/li.strolch.agent/src/main/java/li/strolch/agent/impl/TransientElementMap.java b/li.strolch.agent/src/main/java/li/strolch/agent/impl/TransientElementMap.java
index 7c45d13a0..dd590385a 100644
--- a/li.strolch.agent/src/main/java/li/strolch/agent/impl/TransientElementMap.java
+++ b/li.strolch.agent/src/main/java/li/strolch/agent/impl/TransientElementMap.java
@@ -87,7 +87,7 @@ public abstract class TransientElementMap<T extends StrolchRootElement> implemen
 
 		T t = getBy(tx, StrolchConstants.TEMPLATE, type);
 		if (assertExists && t == null) {
-			String msg = "The template with type {0} does not exist!"; //$NON-NLS-1$
+			String msg = "The template with type '{0}' does not exist!"; //$NON-NLS-1$
 			throw new StrolchException(MessageFormat.format(msg, type));
 		}
 
@@ -116,7 +116,7 @@ public abstract class TransientElementMap<T extends StrolchRootElement> implemen
 		}
 
 		if (assertExists && t == null) {
-			String msg = "The element with type {0} and id {1} does not exist!"; //$NON-NLS-1$
+			String msg = "The element with type '{0}' and id '{1}' does not exist!"; //$NON-NLS-1$
 			throw new StrolchException(MessageFormat.format(msg, type, id));
 		}
 
@@ -135,7 +135,7 @@ public abstract class TransientElementMap<T extends StrolchRootElement> implemen
 		String id = refP.getValue();
 		T t = getBy(tx, type, id, false);
 		if (assertExists && t == null) {
-			String msg = "The element with type {0} and id {1} does not exist for param {2}"; //$NON-NLS-1$
+			String msg = "The element with type '{0}' and id '{1}' does not exist for param '{2}'"; //$NON-NLS-1$
 			throw new StrolchException(MessageFormat.format(msg, type, id, refP.getLocator()));
 		}
 		return t;
@@ -153,7 +153,7 @@ public abstract class TransientElementMap<T extends StrolchRootElement> implemen
 				.map(id -> {
 					T t = getBy(tx, type, id, false);
 					if (assertExists && t == null) {
-						String msg = "The element with type {0} and id {1} does not exist for param {2}"; //$NON-NLS-1$
+						String msg = "The element with type '{0}' and id '{1}' does not exist for param '{2}'"; //$NON-NLS-1$
 						throw new StrolchException(MessageFormat.format(msg, type, id, refP.getLocator()));
 					}
 					return t;
@@ -256,7 +256,7 @@ public abstract class TransientElementMap<T extends StrolchRootElement> implemen
 
 		// assert no object already exists with this id
 		if (byType.containsKey(element.getId())) {
-			String msg = "An element already exists with the id {0}. Elements of the same class must always have a unique id, regardless of their type!"; //$NON-NLS-1$
+			String msg = "An element already exists with the id '{0}'. Elements of the same class must always have a unique id, regardless of their type!"; //$NON-NLS-1$
 			msg = MessageFormat.format(msg, element.getId());
 			throw new StrolchPersistenceException(msg);
 		}
@@ -280,7 +280,7 @@ public abstract class TransientElementMap<T extends StrolchRootElement> implemen
 
 		// assert no object already exists with this id
 		if (byType.containsKey(element.getId())) {
-			String msg = "An element already exists with the id {0}. Elements of the same class must always have a unique id, regardless of their type!"; //$NON-NLS-1$
+			String msg = "An element already exists with the id '{0}'. Elements of the same class must always have a unique id, regardless of their type!"; //$NON-NLS-1$
 			msg = MessageFormat.format(msg, element.getId());
 			throw new StrolchPersistenceException(msg);
 		}
@@ -306,14 +306,14 @@ public abstract class TransientElementMap<T extends StrolchRootElement> implemen
 	private void internalUpdate(StrolchTransaction tx, T element) {
 		Map<String, T> byType = this.elementMap.get(element.getType());
 		if (byType == null) {
-			String msg = "The element does not yet exist with the type {0} and id {1}. Use add() for new objects!"; //$NON-NLS-1$
+			String msg = "The element does not yet exist with the type '{0}' and id '{1}'. Use add() for new objects!"; //$NON-NLS-1$
 			msg = MessageFormat.format(msg, element.getType(), element.getId());
 			throw new StrolchPersistenceException(msg);
 		}
 
 		// assert no object already exists with this id
 		if (!byType.containsKey(element.getId())) {
-			String msg = "The element does not yet exist with the type {0} and id {1}. Use add() for new objects!"; //$NON-NLS-1$
+			String msg = "The element does not yet exist with the type '{0}' and id '{1}'. Use add() for new objects!"; //$NON-NLS-1$
 			msg = MessageFormat.format(msg, element.getType(), element.getId());
 			throw new StrolchPersistenceException(msg);
 		}
diff --git a/li.strolch.agent/src/main/java/li/strolch/persistence/api/AbstractTransaction.java b/li.strolch.agent/src/main/java/li/strolch/persistence/api/AbstractTransaction.java
index 82f7ba909..7fc6c897e 100644
--- a/li.strolch.agent/src/main/java/li/strolch/persistence/api/AbstractTransaction.java
+++ b/li.strolch.agent/src/main/java/li/strolch/persistence/api/AbstractTransaction.java
@@ -613,6 +613,11 @@ public abstract class AbstractTransaction implements StrolchTransaction {
 		DBC.PRE.assertNotNull("refP", refP);
 		ElementMapHelpers.assertIsRefParam(INTERPRETATION_ORDER_REF, refP);
 
+		if (assertExists && refP.isEmpty()) {
+			String msg = "The Order with type '{0}' and id '{1}' does not exist for param '{2}'"; //$NON-NLS-1$
+			throw new StrolchException(MessageFormat.format(msg, refP.getUom(), refP.getValue(), refP.getLocator()));
+		}
+
 		Order element = getElementFromFilter(Tags.ORDER, Order.locatorFor(refP.getUom(), refP.getValue()));
 		if (element != null)
 			return element;
@@ -684,6 +689,11 @@ public abstract class AbstractTransaction implements StrolchTransaction {
 		DBC.PRE.assertNotNull("refP", refP);
 		ElementMapHelpers.assertIsRefParam(INTERPRETATION_RESOURCE_REF, refP);
 
+		if (assertExists && refP.isEmpty()) {
+			String msg = "The Resource with type '{0}' and id '{1}' does not exist for param '{2}'"; //$NON-NLS-1$
+			throw new StrolchException(MessageFormat.format(msg, refP.getUom(), refP.getValue(), refP.getLocator()));
+		}
+
 		Resource element = getElementFromFilter(Tags.RESOURCE, Resource.locatorFor(refP.getUom(), refP.getValue()));
 		if (element != null)
 			return element;
@@ -767,6 +777,11 @@ public abstract class AbstractTransaction implements StrolchTransaction {
 		DBC.PRE.assertNotNull("refP", refP);
 		ElementMapHelpers.assertIsRefParam(INTERPRETATION_ACTIVITY_REF, refP);
 
+		if (assertExists && refP.isEmpty()) {
+			String msg = "The Activity with type '{0}' and id '{1}' does not exist for param '{2}'"; //$NON-NLS-1$
+			throw new StrolchException(MessageFormat.format(msg, refP.getUom(), refP.getValue(), refP.getLocator()));
+		}
+
 		Activity element = getElementFromFilter(Tags.ACTIVITY, Activity.locatorFor(refP.getUom(), refP.getValue()));
 		if (element != null)
 			return element;