diff --git a/.github/workflows/modoboa.yml b/.github/workflows/modoboa.yml
index cacf20a0e..39d8be9ba 100644
--- a/.github/workflows/modoboa.yml
+++ b/.github/workflows/modoboa.yml
@@ -97,7 +97,7 @@ jobs:
           pip install -r mysql-requirements.txt
           echo "DB=mysql" >> $GITHUB_ENV
       - name: Test with pytest
-        if: ${{ matrix.python-version != '3.8' || matrix.database != 'postgres' }}
+        if: ${{ matrix.database != 'postgres' }}
         run: |
           python ./tests.py
           cd test_project
diff --git a/modoboa/admin/models/domain.py b/modoboa/admin/models/domain.py
index dd997b9a6..3cc25bf90 100644
--- a/modoboa/admin/models/domain.py
+++ b/modoboa/admin/models/domain.py
@@ -313,7 +313,8 @@ class Domain(mixins.MessageLimitMixin, AdminObject):
 
     def save(self, *args, **kwargs):
         """Store current data if domain is renamed."""
-        if self.oldname != self.name:
+        # We check that the instance exists to use m2m relationship
+        if self.pk and self.oldname != self.name:
             self.old_mail_homes = {
                 mb.id: mb.mail_home for mb in self.mailbox_set.all()
             }