[fix] Fixed 0010 pki migration when cert serial_number is None

openwisp_controller/pki/migrations/0010_common_name_organization_unique.py

@@ -1,5 +1,7 @@
 # Generated by Django 3.1.12 on 2021-07-06 12:22
 
+from uuid import uuid4
+
 import shortuuid
 from django.db import migrations, models
 from swapper import load_model
@@ -52,6 +54,10 @@ def make_cert_common_name_unique(apps, schema_editor):
             unique_slug = shortuuid.ShortUUID().random(length=8)
             common_name = f'{common_name}-{unique_slug}'
             dupe_cn_cert.common_name = common_name
+            # in some older versions `serial_number` can be None
+            # in this case we'll assign a serial number while renewing
+            if dupe_cn_cert.serial_number is None:
+                dupe_cn_cert.serial_number = uuid4().int
             dupe_cn_cert.renew()