diff --git a/src/yunohost/data_migrations/0002_migrate_to_tsig_sha256.py b/src/yunohost/data_migrations/0002_migrate_to_tsig_sha256.py
index 824245c82..cc5d4c19b 100644
--- a/src/yunohost/data_migrations/0002_migrate_to_tsig_sha256.py
+++ b/src/yunohost/data_migrations/0002_migrate_to_tsig_sha256.py
@@ -19,10 +19,6 @@ class MyMigration(Migration):
 
     "Migrate Dyndns stuff from MD5 TSIG to SHA512 TSIG"
 
-    def backward(self):
-        # Not possible because that's a non-reversible operation ?
-        pass
-
     def migrate(self, dyn_host="dyndns.yunohost.org", domain=None, private_key_path=None):
 
         if domain is None or private_key_path is None:
diff --git a/src/yunohost/data_migrations/0003_migrate_to_stretch.py b/src/yunohost/data_migrations/0003_migrate_to_stretch.py
index 8b7586701..0db6cfd6d 100644
--- a/src/yunohost/data_migrations/0003_migrate_to_stretch.py
+++ b/src/yunohost/data_migrations/0003_migrate_to_stretch.py
@@ -29,11 +29,7 @@ class MyMigration(Migration):
 
     mode = "manual"
 
-    def backward(self):
-
-        raise YunohostError("migration_backward_impossible", name=self.name)
-
-    def migrate(self):
+    def forward(self):
 
         self.logfile = "/var/log/yunohost/{}.log".format(self.name)
 
diff --git a/src/yunohost/data_migrations/0004_php5_to_php7_pools.py b/src/yunohost/data_migrations/0004_php5_to_php7_pools.py
index faf9ccbbc..e916a9cd7 100644
--- a/src/yunohost/data_migrations/0004_php5_to_php7_pools.py
+++ b/src/yunohost/data_migrations/0004_php5_to_php7_pools.py
@@ -24,7 +24,7 @@ class MyMigration(Migration):
 
     dependencies = ["migrate_to_stretch"]
 
-    def migrate(self):
+    def forward(self):
 
         # Get list of php5 pool files
         php5_pool_files = glob.glob("{}/*.conf".format(PHP5_POOLS))
diff --git a/src/yunohost/data_migrations/0005_postgresql_9p4_to_9p6.py b/src/yunohost/data_migrations/0005_postgresql_9p4_to_9p6.py
index 50c0561cb..9cb6e51bd 100644
--- a/src/yunohost/data_migrations/0005_postgresql_9p4_to_9p6.py
+++ b/src/yunohost/data_migrations/0005_postgresql_9p4_to_9p6.py
@@ -16,7 +16,7 @@ class MyMigration(Migration):
 
     dependencies = ["migrate_to_stretch"]
 
-    def migrate(self):
+    def forward(self):
 
         if not self.package_is_installed("postgresql-9.4"):
             logger.warning(m18n.n("migration_0005_postgresql_94_not_installed"))
@@ -34,10 +34,6 @@ class MyMigration(Migration):
         subprocess.check_call("pg_dropcluster --stop 9.4 main", shell=True)
         subprocess.check_call("service postgresql start", shell=True)
 
-    def backward(self):
-
-        pass
-
     def package_is_installed(self, package_name):
 
         p = subprocess.Popen("dpkg --list | grep '^ii ' | grep -q -w {}".format(package_name), shell=True)
diff --git a/src/yunohost/data_migrations/0006_sync_admin_and_root_passwords.py b/src/yunohost/data_migrations/0006_sync_admin_and_root_passwords.py
index cd13d680d..953652111 100644
--- a/src/yunohost/data_migrations/0006_sync_admin_and_root_passwords.py
+++ b/src/yunohost/data_migrations/0006_sync_admin_and_root_passwords.py
@@ -20,16 +20,13 @@ class MyMigration(Migration):
 
     "Synchronize admin and root passwords"
 
-    def migrate(self):
+    def forward(self):
 
         new_hash = self._get_admin_hash()
         self._replace_root_hash(new_hash)
 
         logger.info(m18n.n("root_password_replaced_by_admin_password"))
 
-    def backward(self):
-        pass
-
     @property
     def mode(self):
 
diff --git a/src/yunohost/data_migrations/0007_ssh_conf_managed_by_yunohost_step1.py b/src/yunohost/data_migrations/0007_ssh_conf_managed_by_yunohost_step1.py
index feffdc27c..7ddcec7fd 100644
--- a/src/yunohost/data_migrations/0007_ssh_conf_managed_by_yunohost_step1.py
+++ b/src/yunohost/data_migrations/0007_ssh_conf_managed_by_yunohost_step1.py
@@ -34,7 +34,7 @@ class MyMigration(Migration):
     use the recommended configuration, with an appropriate disclaimer.
     """
 
-    def migrate(self):
+    def forward(self):
 
         # Check if deprecated DSA Host Key is in config
         dsa_rgx = r'^[ \t]*HostKey[ \t]+/etc/ssh/ssh_host_dsa_key[ \t]*(?:#.*)?$'
diff --git a/src/yunohost/data_migrations/0008_ssh_conf_managed_by_yunohost_step2.py b/src/yunohost/data_migrations/0008_ssh_conf_managed_by_yunohost_step2.py
index 0ea0ddc3a..c158192f9 100644
--- a/src/yunohost/data_migrations/0008_ssh_conf_managed_by_yunohost_step2.py
+++ b/src/yunohost/data_migrations/0008_ssh_conf_managed_by_yunohost_step2.py
@@ -35,7 +35,7 @@ class MyMigration(Migration):
 
     dependencies = ["ssh_conf_managed_by_yunohost_step1"]
 
-    def migrate(self):
+    def forward(self):
         settings_set("service.ssh.allow_deprecated_dsa_hostkey", False)
         regen_conf(names=['ssh'], force=True)
 
@@ -44,10 +44,6 @@ class MyMigration(Migration):
         if os.path.isdir(ARCHIVES_PATH):
             chown(ARCHIVES_PATH, uid="admin", gid="root")
 
-    def backward(self):
-
-        raise YunohostError("migration_backward_impossible", name=self.name)
-
     @property
     def mode(self):
 
diff --git a/src/yunohost/data_migrations/0009_decouple_regenconf_from_services.py b/src/yunohost/data_migrations/0009_decouple_regenconf_from_services.py
index d552d7c9c..ffe2279a8 100644
--- a/src/yunohost/data_migrations/0009_decouple_regenconf_from_services.py
+++ b/src/yunohost/data_migrations/0009_decouple_regenconf_from_services.py
@@ -17,7 +17,7 @@ class MyMigration(Migration):
     Decouple the regen conf mechanism from the concept of services
     """
 
-    def migrate(self):
+    def forward(self):
 
         if "conffiles" not in read_file("/etc/yunohost/services.yml") \
            or os.path.exists(REGEN_CONF_FILE):
@@ -37,6 +37,3 @@ class MyMigration(Migration):
         # (Actually save the modification of services)
         _save_services(services)
 
-    def backward(self):
-
-        pass
diff --git a/src/yunohost/data_migrations/0010_migrate_to_apps_json.py b/src/yunohost/data_migrations/0010_migrate_to_apps_json.py
index 43ae9a86f..7092d92c7 100644
--- a/src/yunohost/data_migrations/0010_migrate_to_apps_json.py
+++ b/src/yunohost/data_migrations/0010_migrate_to_apps_json.py
@@ -15,7 +15,7 @@ class MyMigration(Migration):
 
     "Migrate from official.json to apps.json"
 
-    def migrate(self):
+    def forward(self):
 
         # Backup current app list json
         os.system("cp %s %s" % (APPSLISTS_JSON, APPSLISTS_BACKUP))
diff --git a/src/yunohost/data_migrations/0011_setup_group_permission.py b/src/yunohost/data_migrations/0011_setup_group_permission.py
index 05c426936..0e371944e 100644
--- a/src/yunohost/data_migrations/0011_setup_group_permission.py
+++ b/src/yunohost/data_migrations/0011_setup_group_permission.py
@@ -92,7 +92,7 @@ class MyMigration(Migration):
             app_setting(app, 'allowed_users', delete=True)
 
 
-    def migrate(self):
+    def forward(self):
         # Check if the migration can be processed
         ldap_regen_conf_status = regen_conf(names=['slapd'], dry_run=True)
         # By this we check if the have been customized
diff --git a/src/yunohost/tools.py b/src/yunohost/tools.py
index a6379e62b..59758acdf 100644
--- a/src/yunohost/tools.py
+++ b/src/yunohost/tools.py
@@ -1316,7 +1316,7 @@ class Migration(object):
         raise NotImplementedError()
 
     def backward(self):
-        pass
+        raise YunohostError("migration_backward_impossible", name=self.name)
 
     @property
     def disclaimer(self):