diff --git a/src/core/pyros_django/seq_submit/models.py b/src/core/pyros_django/seq_submit/models.py
index 551c27e..0a8e93f 100644
--- a/src/core/pyros_django/seq_submit/models.py
+++ b/src/core/pyros_django/seq_submit/models.py
@@ -352,7 +352,7 @@ class Sequence(models.Model):
     flag = models.CharField(max_length=45, blank=True, null=True)
     period = models.ForeignKey(Period, on_delete=models.DO_NOTHING, related_name="sequence_period", blank=True, null=True)
     #period = models.ForeignKey("Period", on_delete=models.DO_NOTHING, related_name="sequences", blank=True, null=True)
-    quota = models.ForeignKey(Quota, on_delete=models.DO_NOTHING,related_name="sequence_quotas", blank=True, null=True)
+    quota = models.ForeignKey(Quota, on_delete=models.SET_NULL,related_name="sequence_quotas", blank=True, null=True)
 
     start_date = models.DateTimeField(
         blank=True, null=True, default=timezone.now, editable=True)
--
libgit2 0.21.2