diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52654d644..fe992a55b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,12 @@ Classify the change according to the following categories:
     ##### Removed
     ### Patches
 
+## v2.10.1
+### Patches
+- Make **ERPOutageInputs** field **max_outage_duration** required
+- In ERP inputs processing, check that **ElectricUtility** **outage_durations** is not empty before calculating max
+- Respond with validation error if **max_outage_duration** not provided and can't be calculated
+
 ## v2.10.0
 ### Minor Updates
 ##### Added
diff --git a/resilience_stats/api.py b/resilience_stats/api.py
index 3fc8b9aba..97ae92f7c 100644
--- a/resilience_stats/api.py
+++ b/resilience_stats/api.py
@@ -166,9 +166,15 @@ def update_user_dict_with_values_from_reopt(user_dict_key:str, reopt_dict:dict):
                 ## Outage ##
                 critical_loads_kw = reopt_run_meta.ElectricLoadOutputs.dict["critical_load_series_kw"]
                 update_user_dict_with_values_from_reopt("Outage", {"critical_loads_kw": critical_loads_kw})
-                update_user_dict_with_values_from_reopt("Outage", {
-                    "max_outage_duration": max(reopt_run_meta.ElectricUtilityInputs.dict["outage_durations"])
-                })
+                if len(reopt_run_meta.ElectricUtilityInputs.dict["outage_durations"]) > 0:
+                    update_user_dict_with_values_from_reopt("Outage", {
+                        "max_outage_duration": max(reopt_run_meta.ElectricUtilityInputs.dict["outage_durations"])
+                    })
+                if bundle.data.get("Outage", {}).get("max_outage_duration",None) is None:
+                    add_validation_err_msg_and_raise_400_response(
+                        meta_dict, 
+                        "You must provide Outage max_outage_duration or the reopt_run_uuid of an optimization where ElectricUtility outage_durations was provided."
+                    )
 
                 ## Generator ##
                 try:
diff --git a/resilience_stats/migrations/0012_alter_erpoutageinputs_max_outage_duration.py b/resilience_stats/migrations/0012_alter_erpoutageinputs_max_outage_duration.py
new file mode 100644
index 000000000..0d46cf305
--- /dev/null
+++ b/resilience_stats/migrations/0012_alter_erpoutageinputs_max_outage_duration.py
@@ -0,0 +1,19 @@
+# Generated by Django 4.0.4 on 2023-03-24 17:35
+
+import django.core.validators
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('resilience_stats', '0011_alter_erpgeneratorinputs_electric_efficiency_half_load_and_more'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='erpoutageinputs',
+            name='max_outage_duration',
+            field=models.IntegerField(help_text='Maximum outage duration modeled', validators=[django.core.validators.MinValueValidator(1), django.core.validators.MaxValueValidator(672)]),
+        ),
+    ]
diff --git a/resilience_stats/models.py b/resilience_stats/models.py
index 62b50f6ba..330f28a07 100644
--- a/resilience_stats/models.py
+++ b/resilience_stats/models.py
@@ -493,8 +493,6 @@ class ERPOutageInputs(BaseModel, models.Model):
         related_name="ERPOutageInputs"
     )
     max_outage_duration = models.IntegerField(
-        blank=True,
-        default=336,
         validators=[
             MinValueValidator(1),
             MaxValueValidator(672),