diff --git a/build.gradle b/build.gradle
index 4206848..9d57db0 100644
--- a/build.gradle
+++ b/build.gradle
@@ -25,4 +25,6 @@ dependencies {
     compile group: 'de.jensd', name: 'fontawesomefx', version: '8.9'
     compile group: 'org.controlsfx', name: 'controlsfx', version: '8.40.11'
     compile group: 'com.google.code.gson', name: 'gson', version: '2.7'
+    compile group: 'org.apache.logging.log4j', name: 'log4j-api', version: '2.6.2'
+    compile group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.6.2'
 }
diff --git a/src/main/java/ninja/javafx/smartcsv/fx/list/ErrorSideBar.java b/src/main/java/ninja/javafx/smartcsv/fx/list/ErrorSideBar.java
index 24339f4..cca48f6 100644
--- a/src/main/java/ninja/javafx/smartcsv/fx/list/ErrorSideBar.java
+++ b/src/main/java/ninja/javafx/smartcsv/fx/list/ErrorSideBar.java
@@ -38,6 +38,8 @@ import javafx.scene.text.Text;
 import ninja.javafx.smartcsv.fx.table.model.CSVModel;
 import ninja.javafx.smartcsv.fx.util.ColorConstants;
 import ninja.javafx.smartcsv.validation.ValidationError;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 import org.controlsfx.control.PopOver;
 
 import java.util.ArrayList;
@@ -54,6 +56,8 @@ import static ninja.javafx.smartcsv.fx.util.I18nValidationUtil.getI18nValidatioM
  */
 public class ErrorSideBar extends Region {
 
+    private static final Logger logger = LogManager.getLogger(ErrorSideBar.class);
+
     private static final double WIDTH = 20.0;
     private static final int BORDER = 8;
     private static final double STATUS_BLOCK_HEIGHT = WIDTH - BORDER;
@@ -133,7 +137,7 @@ public class ErrorSideBar extends Region {
                 statusBlock.setStyle("-fx-background-color: " + ERROR_COLOR);
 
                 int rows = model.get().getRows().size();
-                double space = heightWithoutStatusBlock() / rows;
+                double space = (double)heightWithoutStatusBlock() / rows;
                 for (ValidationError error : errorList) {
                     errorMarkerList.add(generateErrorMarker(space, error));
                 }
@@ -147,6 +151,8 @@ public class ErrorSideBar extends Region {
     }
 
     private Region generateErrorMarker(double space, ValidationError error) {
+        logger.info("generate error marker for {} errors in line {}", error.getMessages().size(), error.getLineNumber());
+        logger.info("layout y is set to {}", (space * error.getLineNumber() + STATUS_BLOCK_OFFSET));
         Region errorMarker = new Region();
         errorMarker.setLayoutY(space * error.getLineNumber() + STATUS_BLOCK_OFFSET);
         errorMarker.setPrefSize(WIDTH, 2);
diff --git a/src/main/java/ninja/javafx/smartcsv/fx/table/model/CSVModel.java b/src/main/java/ninja/javafx/smartcsv/fx/table/model/CSVModel.java
index 1063821..64c8312 100644
--- a/src/main/java/ninja/javafx/smartcsv/fx/table/model/CSVModel.java
+++ b/src/main/java/ninja/javafx/smartcsv/fx/table/model/CSVModel.java
@@ -31,6 +31,8 @@ import javafx.collections.ObservableList;
 import ninja.javafx.smartcsv.validation.ValidationConfiguration;
 import ninja.javafx.smartcsv.validation.ValidationError;
 import ninja.javafx.smartcsv.validation.Validator;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -41,6 +43,8 @@ import java.util.List;
  */
 public class CSVModel {
 
+    private static final Logger logger = LogManager.getLogger(CSVModel.class);
+
     private Validator validator;
     private ObservableList<CSVRow> rows = FXCollections.observableArrayList();
     private String[] header;
@@ -103,6 +107,8 @@ public class CSVModel {
     public void revalidate() {
         validationError.clear();
 
+        logger.info("revalidate: hasValidator -> {}", hasValidator());
+
         if (!hasValidator()) return;
 
         List<ValidationError> errors = new ArrayList<>();
@@ -110,6 +116,7 @@ public class CSVModel {
         if (header != null) {
             ValidationError headerError = validator.isHeaderValid(header);
             if (headerError != null) {
+                logger.info("revalidate: header error found");
                 errors.add(headerError);
             }
         }
@@ -123,6 +130,7 @@ public class CSVModel {
                 if (validator != null) {
                     ValidationError validationError = validator.isValid(column, value.getValue(), lineNumber);
                     if (validationError != null) {
+                        logger.info("revalidate: {} errors found in line {}", validationError.getMessages().size(), lineNumber);
                         errors.add(validationError);
                         value.setValidationError(validationError);
                     } else {
diff --git a/src/main/resources/log4j2.xml b/src/main/resources/log4j2.xml
new file mode 100644
index 0000000..4c71d59
--- /dev/null
+++ b/src/main/resources/log4j2.xml
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration status="error">
+
+    <Properties>
+        <Property name="filename">smartcsv.log</Property>
+    </Properties>
+    <ThresholdFilter level="trace"/>
+
+    <Appenders>
+        <Console name="Console" target="SYSTEM_OUT">
+            <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
+        </Console>
+
+        <File name="File" fileName="${filename}" bufferedIO="true">
+            <PatternLayout>
+                <pattern>%d %p %C{1.} [%t] %m%n</pattern>
+            </PatternLayout>
+        </File>
+    </Appenders>
+    <Loggers>
+        <Root level="error">
+            <AppenderRef ref="File"/>
+            <AppenderRef ref="Console"/>
+        </Root>
+    </Loggers>
+</Configuration>
\ No newline at end of file