diff --git a/src/main/java/ch/ethz/seb/sebserver/gbl/api/POSTMapper.java b/src/main/java/ch/ethz/seb/sebserver/gbl/api/POSTMapper.java
index 145be78c..4cc325b2 100644
--- a/src/main/java/ch/ethz/seb/sebserver/gbl/api/POSTMapper.java
+++ b/src/main/java/ch/ethz/seb/sebserver/gbl/api/POSTMapper.java
@@ -15,6 +15,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.function.Function;
 import java.util.stream.Collectors;
@@ -247,14 +248,20 @@ public class POSTMapper {
                 .map(ts -> {
                     try {
                         final String[] split = StringUtils.split(ts, Constants.EMBEDDED_LIST_SEPARATOR);
-                        return new Threshold(Double.parseDouble(
-                                split[0]),
-                                (split.length > 1) ? split[1] : null,
-                                (split.length > 2) ? split[2] : null);
+                        Double val = null;
+                        try {
+                            val = Double.parseDouble(split[0]);
+                        } catch (final Exception e) {
+                        }
+                        return new Threshold(
+                                val,
+                                (split.length > 1) ? Utils.parseColorString(Utils.parseRGB(split[1])) : null,
+                                (split.length > 2 && "null".equals(split[2])) ? split[2] : null);
                     } catch (final Exception e) {
                         return null;
                     }
                 })
+                .filter(Objects::nonNull)
                 .collect(Collectors.toList());
     }
 
diff --git a/src/main/java/ch/ethz/seb/sebserver/gbl/util/Utils.java b/src/main/java/ch/ethz/seb/sebserver/gbl/util/Utils.java
index 73687a48..2f1bd980 100644
--- a/src/main/java/ch/ethz/seb/sebserver/gbl/util/Utils.java
+++ b/src/main/java/ch/ethz/seb/sebserver/gbl/util/Utils.java
@@ -578,6 +578,9 @@ public final class Utils {
      * @param rgb foreground or text color
      * @return true of the background color for given foreground color shall be dark or false if it shall be light */
     public static boolean darkColorContrast(final RGB rgb) {
+        if (rgb == null) {
+            return true;
+        }
         return rgb.red + rgb.green + rgb.blue > DARK_COLOR_THRESHOLD;
     }
 
@@ -592,15 +595,16 @@ public final class Utils {
     }
 
     public static RGB parseRGB(final String colorString) {
-        if (StringUtils.isBlank(colorString)) {
+        try {
+
+            final int r = Integer.parseInt(colorString.substring(0, 2), 16);
+            final int g = Integer.parseInt(colorString.substring(2, 4), 16);
+            final int b = Integer.parseInt(colorString.substring(4, 6), 16);
+
+            return new RGB(r, g, b);
+        } catch (final Exception e) {
             return null;
         }
-
-        final int r = Integer.parseInt(colorString.substring(0, 2), 16);
-        final int g = Integer.parseInt(colorString.substring(2, 4), 16);
-        final int b = Integer.parseInt(colorString.substring(4, 6), 16);
-
-        return new RGB(r, g, b);
     }
 
     public static String toColorFractionString(final int fraction) {
diff --git a/src/main/java/ch/ethz/seb/sebserver/gui/widget/ThresholdList.java b/src/main/java/ch/ethz/seb/sebserver/gui/widget/ThresholdList.java
index dcdfc08f..14bf03b5 100644
--- a/src/main/java/ch/ethz/seb/sebserver/gui/widget/ThresholdList.java
+++ b/src/main/java/ch/ethz/seb/sebserver/gui/widget/ThresholdList.java
@@ -121,11 +121,12 @@ public final class ThresholdList extends Composite {
 
     public Collection<Threshold> getThresholds() {
         removeInvalidListEntries();
-        return this.thresholds
+        final List<Threshold> collect = this.thresholds
                 .stream()
                 .map(entry -> new Threshold(entry.getValue(), entry.getColor(),
                         null /* TODO add icon selection here */))
                 .collect(Collectors.toList());
+        return collect;
     }
 
     private void removeInvalidListEntries() {