diff -up src/sage/databases/cremona.py.orig src/sage/databases/cremona.py
--- src/sage/databases/cremona.py.orig	2019-06-26 14:41:04.000000000 -0600
+++ src/sage/databases/cremona.py	2019-09-09 15:37:13.321511378 -0600
@@ -842,7 +842,8 @@ class MiniCremonaDatabase(SQLDatabase):
                 message = "There is no elliptic curve with label " \
                     + label + " in the default database; try installing " \
                     + "the optional package database_cremona_ellcurve which " \
-                    + "contains the complete Cremona database"
+                    + "contains the complete Cremona database: " \
+                    + "sudo dnf install sagemath-data-elliptic_curves_large"
             raise ValueError(message)
         ainvs = eval(c[0])
         data = {'cremona_label': label,
@@ -1640,6 +1641,7 @@ class LargeCremonaDatabase(MiniCremonaDa
             con.executemany("UPDATE t_curve SET gens=? WHERE curve=?", \
                 curve_data)
             print("Committing...")
+            self.commit()
             if largest_conductor and int(v[0]) > largest_conductor: break
 
 _db = None