diff --git a/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/rollout/rollout/DefineGroupsLayout.java b/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/rollout/rollout/DefineGroupsLayout.java
index a58cdcf0de..0941da26cf 100644
--- a/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/rollout/rollout/DefineGroupsLayout.java
+++ b/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/rollout/rollout/DefineGroupsLayout.java
@@ -48,6 +48,7 @@
 import com.vaadin.data.Validator;
 import com.vaadin.data.util.converter.StringToFloatConverter;
 import com.vaadin.data.util.converter.StringToIntegerConverter;
+import com.vaadin.data.validator.RangeValidator;
 import com.vaadin.data.validator.FloatRangeValidator;
 import com.vaadin.data.validator.IntegerRangeValidator;
 import com.vaadin.server.FontAwesome;
@@ -62,6 +63,8 @@
 import com.vaadin.ui.TextField;
 import com.vaadin.ui.UI;
 
+import static org.eclipse.hawkbit.ui.utils.HawkbitCommonUtil.getCurrentLocale;
+
 /**
  * Define groups for a Rollout
  */
@@ -331,8 +334,13 @@ private void setGroupsValidation(final RolloutGroupsValidation validation) {
         }
 
         // validate the single groups
-        final int maxTargets = quotaManagement.getMaxTargetsPerRolloutGroup();
+        singleGroupsValidation(lastRow);
+    }
+
+    private void singleGroupsValidation(final GroupRow lastRow) {
         final boolean hasRemainingTargetsError = validationStatus == ValidationStatus.INVALID;
+        final int maxTargets = quotaManagement.getMaxTargetsPerRolloutGroup();
+
         for (int i = 0; i < groupRows.size(); ++i) {
             final GroupRow row = groupRows.get(i);
             // do not mask the 'remaining targets' error
@@ -340,13 +348,14 @@ private void setGroupsValidation(final RolloutGroupsValidation validation) {
                 continue;
             }
             row.resetError();
-            final Long count = groupsValidation.getTargetsPerGroup().get(i);
-            if (count != null && count > maxTargets) {
-                row.setError(i18n.getMessage(MESSAGE_ROLLOUT_MAX_GROUP_SIZE_EXCEEDED, maxTargets));
-                setValidationStatus(ValidationStatus.INVALID);
+            if (groupsValidation != null) {
+                final Long count = groupsValidation.getTargetsPerGroup().get(i);
+                if (count != null && count > maxTargets) {
+                    row.setError(i18n.getMessage(MESSAGE_ROLLOUT_MAX_GROUP_SIZE_EXCEEDED, maxTargets));
+                    setValidationStatus(ValidationStatus.INVALID);
+                }
             }
         }
-
     }
 
     private List<RolloutGroupCreate> getGroupsFromRows() {
@@ -463,12 +472,16 @@ private void removeGroupRow(final GroupRow groupRow) {
         private void validateMandatoryPercentage(final Object value) {
             if (value != null) {
                 final String message = i18n.getMessage("message.rollout.field.value.range", 0, 100);
+                RangeValidator rangeValidator;
                 if (value instanceof Float) {
-                    new FloatRangeValidator(message, 0F, 100F).validate(value);
-                }
-                if (value instanceof Integer) {
-                    new IntegerRangeValidator(message, 0, 100).validate(value);
+                    rangeValidator = new FloatRangeValidator(message, 0F, 100F);
+                } else if (value instanceof Integer) {
+                    rangeValidator = new IntegerRangeValidator(message, 0, 100);
+                } else {
+                    throw new Validator.InvalidValueException(i18n.getMessage("message.enter.number"));
                 }
+                rangeValidator.setMinValueIncluded(false);
+                rangeValidator.validate(value);
             } else {
                 throw new Validator.EmptyValueException(i18n.getMessage("message.enter.number"));
             }
@@ -615,7 +628,7 @@ public void populateByGroup(final RolloutGroup group) {
             targetFilterQuery.setValue(group.getTargetFilterQuery());
             populateTargetFilterQuery(group);
 
-            targetPercentage.setValue(String.format("%.2f", group.getTargetPercentage()));
+            targetPercentage.setValue(String.format(getCurrentLocale(), "%.2f", group.getTargetPercentage()));
             triggerThreshold.setValue(group.getSuccessConditionExp());
             errorThreshold.setValue(group.getErrorConditionExp());