diff --git a/tests/test_sessions.py b/tests/test_sessions.py
index 1b969383d..c187206fc 100644
--- a/tests/test_sessions.py
+++ b/tests/test_sessions.py
@@ -240,11 +240,14 @@ def test_transient_data_removal(pub, app):
 
     assert sql.Session.count() == 1
     assert sql.TransientData.count() == 1
+    transient_data = sql.TransientData.select()[0]
 
     app.get('/logout')
     assert sql.Session.count() == 0
     assert sql.TransientData.count() == 0
 
+    transient_data.store()  # session_id not found, should not fail
+
 
 def test_magictoken_migration(pub, app):
     pub.session_manager.session_class.wipe()
diff --git a/wcs/sql.py b/wcs/sql.py
index 75397daaa..09c0a887c 100644
--- a/wcs/sql.py
+++ b/wcs/sql.py
@@ -3394,7 +3394,11 @@ class TransientData(SqlMixin):
             ', '.join(['%%(%s)s' % x for x in column_names]),
             ', '.join(['%s = %%(%s)s' % (x, x) for x in column_names]),
         )
-        cur.execute(sql_statement, sql_dict)
+        try:
+            cur.execute(sql_statement, sql_dict)
+        except psycopg2.IntegrityError as e:
+            if "transient_data_session_id_fkey" not in str(e):
+                raise
 
         conn.commit()
         cur.close()