diff --git a/src/PamController/PamguardVersionInfo.java b/src/PamController/PamguardVersionInfo.java
index 7172293c..3c36d956 100644
--- a/src/PamController/PamguardVersionInfo.java
+++ b/src/PamController/PamguardVersionInfo.java
@@ -24,14 +24,14 @@ public class PamguardVersionInfo {
 	 * PAMGuard can work with. 
 	 */
 	static public final String minJavaVersion = "11.0.0";
-	static public final String maxJavaVersion = "19.99.99";
+	static public final String maxJavaVersion = "21.99.99";
 	
 
 	/**
 	 * Version number, major version.minorversion.sub-release.
 	 * Note: can't go higher than sub-release 'f'
 	 */
-	static public final String version = "2.02.09c";
+	static public final String version = "2.02.09d";
 	
 	/**
 	 * Release date
diff --git a/src/offlineProcessing/OfflineTask.java b/src/offlineProcessing/OfflineTask.java
index 7f3e0ec1..42f710d7 100644
--- a/src/offlineProcessing/OfflineTask.java
+++ b/src/offlineProcessing/OfflineTask.java
@@ -383,6 +383,9 @@ public abstract class OfflineTask<T extends PamDataUnit> {
 		}
 
 		for (PamDataBlock aBlock:affectedDataBlocks) {
+			if (aBlock == parentDataBlock) {
+				continue;
+			}
 			deleteOldData(aBlock, taskGroupParams);
 		}
 	}
diff --git a/src/pamMaths/HistogramDisplay.java b/src/pamMaths/HistogramDisplay.java
index 771910c0..615c4ca0 100644
--- a/src/pamMaths/HistogramDisplay.java
+++ b/src/pamMaths/HistogramDisplay.java
@@ -407,6 +407,9 @@ public class HistogramDisplay extends Object implements Observer {
 		public void updateWindow() {
 			int nRows = rowLabels.length;
 			int iRow;
+			if (numbers == null || numbers.length == 0) {
+				return;
+			}
 			// check all the controls are there and lay them out
 			if (numbers == null || numbers.length != pamHistograms.size() || 
 					numbers[0].length != rowLabels.length || selectedStats != oldStatsSelection) {