diff --git a/modules/flowable-cmmn-engine/src/main/java/org/flowable/cmmn/engine/impl/behavior/impl/TimerEventListenerActivityBehaviour.java b/modules/flowable-cmmn-engine/src/main/java/org/flowable/cmmn/engine/impl/behavior/impl/TimerEventListenerActivityBehaviour.java
index 3455ba75b43..f0891da6b65 100644
--- a/modules/flowable-cmmn-engine/src/main/java/org/flowable/cmmn/engine/impl/behavior/impl/TimerEventListenerActivityBehaviour.java
+++ b/modules/flowable-cmmn-engine/src/main/java/org/flowable/cmmn/engine/impl/behavior/impl/TimerEventListenerActivityBehaviour.java
@@ -51,6 +51,8 @@
 import org.flowable.job.service.impl.persistence.entity.TimerJobEntity;
 import org.flowable.job.service.impl.persistence.entity.TimerJobEntityManager;
 import org.joda.time.DateTime;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * {@link CmmnActivityBehavior} implementation for the CMMN Timer Event Listener.
@@ -59,6 +61,8 @@
  */
 public class TimerEventListenerActivityBehaviour extends CoreCmmnActivityBehavior implements PlanItemActivityBehavior {
 
+    private static final Logger LOGGER = LoggerFactory.getLogger(TimerEventListenerActivityBehaviour.class);
+
     protected TimerEventListener timerEventListener;
 
     public TimerEventListenerActivityBehaviour(TimerEventListener timerEventListener) {
@@ -130,14 +134,18 @@ protected void handleCreateTransition(CommandContext commandContext, PlanItemIns
                     // Try to parse as ISO8601 first
                     try {
                         timerDueDate = DateUtil.parseDate(timerString);
-                    } catch (Exception e) { }
+                    } catch (Exception e) {
+                        LOGGER.debug("Failed to parse timer expression '{}' as ISO8601 date", timerString, e);
+                    }
 
                     // Try to parse as cron expression
                     try {
                         timerDueDate = businessCalendarManager.getBusinessCalendar(CycleBusinessCalendar.NAME).resolveDuedate(timerString);
                         isRepeating = true;
 
-                    } catch (Exception pe) { }
+                    } catch (Exception pe) {
+                        LOGGER.debug("Failed to parse timer expression '{}' as cron expression", timerString, pe);
+                    }
 
                 }
 
diff --git a/modules/flowable-engine-common/src/main/java/org/flowable/common/engine/impl/de/odysseus/el/ExpressionFactoryImpl.java b/modules/flowable-engine-common/src/main/java/org/flowable/common/engine/impl/de/odysseus/el/ExpressionFactoryImpl.java
index 4843ca74e88..1c86718a9d3 100644
--- a/modules/flowable-engine-common/src/main/java/org/flowable/common/engine/impl/de/odysseus/el/ExpressionFactoryImpl.java
+++ b/modules/flowable-engine-common/src/main/java/org/flowable/common/engine/impl/de/odysseus/el/ExpressionFactoryImpl.java
@@ -32,6 +32,8 @@
 import org.flowable.common.engine.impl.javax.el.ELContext;
 import org.flowable.common.engine.impl.javax.el.ELException;
 import org.flowable.common.engine.impl.javax.el.ExpressionFactory;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Expression factory implementation.
@@ -75,6 +77,8 @@
  * @author Christoph Beck
  */
 public class ExpressionFactoryImpl extends ExpressionFactory {
+
+	private static final Logger LOGGER = LoggerFactory.getLogger(ExpressionFactoryImpl.class);
 	/**
 	 * A profile provides a default set of language features that will define the builder's
 	 * behavior. A profile can be adjusted using the <code>javax.el.methodInvocations</code>,
@@ -266,7 +270,7 @@ private Properties loadDefaultProperties() {
 					try {
 						input.close();
 					} catch (IOException e) {
-						// ignore...
+						LOGGER.debug("Failed to close stream while loading default properties", e);
 					}
 				}
 				if (getClass().getName().equals(properties.getProperty("javax.el.ExpressionFactory"))) {
@@ -274,7 +278,7 @@ private Properties loadDefaultProperties() {
 				}
 			}
 		} catch (SecurityException e) {
-			// ignore...
+			LOGGER.debug("SecurityException while loading default properties", e);
 		}
 		if (getClass().getName().equals(System.getProperty("javax.el.ExpressionFactory"))) {
 			return System.getProperties();