diff --git a/src/main/java/org/breedinginsight/brapps/importer/services/processors/ExperimentProcessor.java b/src/main/java/org/breedinginsight/brapps/importer/services/processors/ExperimentProcessor.java
index 4f8d85b1b..a5fedaf84 100644
--- a/src/main/java/org/breedinginsight/brapps/importer/services/processors/ExperimentProcessor.java
+++ b/src/main/java/org/breedinginsight/brapps/importer/services/processors/ExperimentProcessor.java
@@ -972,7 +972,11 @@ private void validateUniqueObsUnits(
             String errorMessage = String.format("The ID (%s) is not unique within the environment(%s)", importRow.getExpUnitId(), importRow.getEnv());
             this.addRowError(Columns.EXP_UNIT_ID, errorMessage, validationErrors, rowNum);
         } else {
-            uniqueStudyAndObsUnit.add(envIdPlusStudyId);
+            //Only want to add valid unique study-obs unit combos
+            //To avoid situations like system counting a null value as a unique combo
+            if (!envIdPlusStudyId.isBlank()) {
+                uniqueStudyAndObsUnit.add(envIdPlusStudyId);
+            }
         }
     }
 
diff --git a/src/main/java/org/breedinginsight/brapps/importer/services/processors/experiment/ExperimentUtilities.java b/src/main/java/org/breedinginsight/brapps/importer/services/processors/experiment/ExperimentUtilities.java
index d3e4dc1e2..ae015aab6 100644
--- a/src/main/java/org/breedinginsight/brapps/importer/services/processors/experiment/ExperimentUtilities.java
+++ b/src/main/java/org/breedinginsight/brapps/importer/services/processors/experiment/ExperimentUtilities.java
@@ -169,13 +169,19 @@ public static String createObservationUnitKey(ExperimentObservation importRow) {
      *
      * This method takes in the name of a study and the name of an observation unit and concatenates them to create a unique key.
      *
+     * If one or both of the inputs is null, returns an empty string since not a valid combination
+     *
      * @param studyName The name of the study
      * @param obsUnitName The name of the observation unit
      * @return A string representing the unique key formed by concatenating the study name and observation unit name
      */
     public static String createObservationUnitKey(String studyName, String obsUnitName) {
         // Concatenate the study name and observation unit name to create the unique key
-        return studyName + obsUnitName;
+        if (studyName != null && obsUnitName != null) {
+            return studyName + obsUnitName;
+        } else {
+            return "";
+        }
     }
 
 // Module/Script-level documentation
diff --git a/src/main/java/org/breedinginsight/brapps/importer/services/processors/experiment/create/workflow/steps/ValidatePendingImportObjectsStep.java b/src/main/java/org/breedinginsight/brapps/importer/services/processors/experiment/create/workflow/steps/ValidatePendingImportObjectsStep.java
index 99fbc12eb..b1391c483 100644
--- a/src/main/java/org/breedinginsight/brapps/importer/services/processors/experiment/create/workflow/steps/ValidatePendingImportObjectsStep.java
+++ b/src/main/java/org/breedinginsight/brapps/importer/services/processors/experiment/create/workflow/steps/ValidatePendingImportObjectsStep.java
@@ -290,7 +290,11 @@ private void validateUniqueObsUnits(
             String errorMessage = String.format("The ID (%s) is not unique within the environment(%s)", importRow.getExpUnitId(), importRow.getEnv());
             ExperimentUtilities.addRowError(ExperimentObservation.Columns.EXP_UNIT_ID, errorMessage, validationErrors, rowNum);
         } else {
-            uniqueStudyAndObsUnit.add(envIdPlusStudyId);
+            //Only want to add valid unique study-obs unit combos
+            //To avoid situations like system counting a null value as a unique combo
+            if (!envIdPlusStudyId.isBlank()) {
+                uniqueStudyAndObsUnit.add(envIdPlusStudyId);
+            }
         }
     }