diff --git a/manila/db/sqlalchemy/api.py b/manila/db/sqlalchemy/api.py
index 08a4c6f649..b2aa05de26 100644
--- a/manila/db/sqlalchemy/api.py
+++ b/manila/db/sqlalchemy/api.py
@@ -1308,6 +1308,12 @@ def _extract_share_instance_values(values):
     return share_instance_values, share_values
 
 
+def _change_size_to_instance_size(snap_instance_values):
+    if 'size' in snap_instance_values:
+        snap_instance_values['instance_size'] = snap_instance_values['size']
+        snap_instance_values.pop('size')
+
+
 def _extract_snapshot_instance_values(values):
     fields = ['status', 'progress', 'provider_location']
     snapshot_instance_values, snapshot_values = (
@@ -2313,6 +2319,8 @@ def share_snapshot_instance_create(context, snapshot_id, values, session=None):
     session = session or get_session()
     values = copy.deepcopy(values)
 
+    _change_size_to_instance_size(values)
+
     if not values.get('id'):
         values['id'] = uuidutils.generate_uuid()
     values.update({'snapshot_id': snapshot_id})
@@ -2330,6 +2338,7 @@ def share_snapshot_instance_update(context, instance_id, values):
     session = get_session()
     instance_ref = share_snapshot_instance_get(context, instance_id,
                                                session=session)
+    _change_size_to_instance_size(values)
 
     # NOTE(u_glide): Ignore updates to custom properties
     for extra_key in models.ShareSnapshotInstance._extra_keys:
@@ -4651,6 +4660,8 @@ def share_group_snapshot_member_create(context, values):
     if not values.get('id'):
         values['id'] = six.text_type(uuidutils.generate_uuid())
 
+    _change_size_to_instance_size(values)
+
     session = get_session()
     with session.begin():
         member.update(values)
@@ -4663,6 +4674,7 @@ def share_group_snapshot_member_create(context, values):
 @require_context
 def share_group_snapshot_member_update(context, member_id, values):
     session = get_session()
+    _change_size_to_instance_size(values)
     with session.begin():
         member = share_group_snapshot_member_get(
             context, member_id, session=session)
diff --git a/manila/db/sqlalchemy/models.py b/manila/db/sqlalchemy/models.py
index 0d2fa62f8b..0b98a01347 100644
--- a/manila/db/sqlalchemy/models.py
+++ b/manila/db/sqlalchemy/models.py
@@ -751,6 +751,14 @@ class ShareSnapshotInstance(BASE, ManilaBase):
         # with share drivers
         return self.share_instance_id
 
+    @property
+    def size(self):
+        # NOTE(silvacarlose) for backwards compatibility
+        if self.instance_size is None:
+            return self.snapshot.size
+        else:
+            return self.instance_size
+
     id = Column(String(36), primary_key=True)
     deleted = Column(String(36), default='False')
     snapshot_id = Column(String(36), nullable=True)
@@ -760,7 +768,7 @@ class ShareSnapshotInstance(BASE, ManilaBase):
     progress = Column(String(255))
     provider_location = Column(String(255))
     share_proto = Column(String(255))
-    size = Column(Integer)
+    instance_size = Column('size', Integer)
     share_group_snapshot_id = Column(String(36), nullable=True)
     user_id = Column(String(255))
     project_id = Column(String(255))
diff --git a/releasenotes/notes/fix-py3-netapp-a9815186ddc865d4.yaml b/releasenotes/notes/fix-py3-netapp-a9815186ddc865d4.yaml
new file mode 100644
index 0000000000..ef0d6c926b
--- /dev/null
+++ b/releasenotes/notes/fix-py3-netapp-a9815186ddc865d4.yaml
@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixed the size value not being present in share snapshot
+    instances, which caused the NetApp driver to crash when
+    creating a share from a snapshot using python3.