use BigIntegerField for a hugher range ;-)

InvenTree/InvenTree/models.py

@@ -84,7 +84,7 @@ class ReferenceIndexingMixin(models.Model):
 
         self.reference_int = ref_int
 
-    reference_int = models.IntegerField(default=0)
+    reference_int = models.BigIntegerField(default=0)
 
 
 class InvenTreeAttachment(models.Model):

InvenTree/build/migrations/0034_alter_build_reference_int.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.5 on 2021-12-01 21:39
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('build', '0033_auto_20211128_0151'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='build',
+            name='reference_int',
+            field=models.BigIntegerField(default=0),
+        ),
+    ]

InvenTree/order/migrations/0054_auto_20211201_2139.py

@@ -0,0 +1,23 @@
+# Generated by Django 3.2.5 on 2021-12-01 21:39
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('order', '0053_auto_20211128_0151'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='purchaseorder',
+            name='reference_int',
+            field=models.BigIntegerField(default=0),
+        ),
+        migrations.AlterField(
+            model_name='salesorder',
+            name='reference_int',
+            field=models.BigIntegerField(default=0),
+        ),
+    ]