diff --git a/src/yunohost/app.py b/src/yunohost/app.py
index 88deb5b6b..011c953e0 100644
--- a/src/yunohost/app.py
+++ b/src/yunohost/app.py
@@ -534,6 +534,7 @@ def app_upgrade(app=[], url=None, file=None, force=False, no_safety_backup=False
     )
     from yunohost.permission import permission_sync_to_user
     from yunohost.regenconf import manually_modified_files
+    from yunohost.utils.legacy import _patch_legacy_php_versions, _patch_legacy_helpers
 
     apps = app
     # Check if disk space available
@@ -790,6 +791,7 @@ def app_install(
         permission_sync_to_user,
     )
     from yunohost.regenconf import manually_modified_files
+    from yunohost.utils.legacy import _patch_legacy_php_versions, _patch_legacy_helpers
 
     # Check if disk space available
     if free_space_in_directory("/") <= 512 * 1000 * 1000:
@@ -2769,213 +2771,3 @@ def _assert_system_is_sane_for_app(manifest, when):
             raise YunohostValidationError("dpkg_is_broken")
         elif when == "post":
             raise YunohostError("this_action_broke_dpkg")
-
-
-LEGACY_PHP_VERSION_REPLACEMENTS = [
-    ("/etc/php5", "/etc/php/7.3"),
-    ("/etc/php/7.0", "/etc/php/7.3"),
-    ("/var/run/php5-fpm", "/var/run/php/php7.3-fpm"),
-    ("/var/run/php/php7.0-fpm", "/var/run/php/php7.3-fpm"),
-    ("php5", "php7.3"),
-    ("php7.0", "php7.3"),
-    (
-        'phpversion="${phpversion:-7.0}"',
-        'phpversion="${phpversion:-7.3}"',
-    ),  # Many helpers like the composer ones use 7.0 by default ...
-    (
-        '"$phpversion" == "7.0"',
-        '$(bc <<< "$phpversion >= 7.3") -eq 1',
-    ),  # patch ynh_install_php to refuse installing/removing php <= 7.3
-]
-
-
-def _patch_legacy_php_versions(app_folder):
-
-    files_to_patch = []
-    files_to_patch.extend(glob.glob("%s/conf/*" % app_folder))
-    files_to_patch.extend(glob.glob("%s/scripts/*" % app_folder))
-    files_to_patch.extend(glob.glob("%s/scripts/*/*" % app_folder))
-    files_to_patch.extend(glob.glob("%s/scripts/.*" % app_folder))
-    files_to_patch.append("%s/manifest.json" % app_folder)
-    files_to_patch.append("%s/manifest.toml" % app_folder)
-
-    for filename in files_to_patch:
-
-        # Ignore non-regular files
-        if not os.path.isfile(filename):
-            continue
-
-        c = (
-            "sed -i "
-            + "".join(
-                "-e 's@{pattern}@{replace}@g' ".format(pattern=p, replace=r)
-                for p, r in LEGACY_PHP_VERSION_REPLACEMENTS
-            )
-            + "%s" % filename
-        )
-        os.system(c)
-
-
-def _patch_legacy_php_versions_in_settings(app_folder):
-
-    settings = read_yaml(os.path.join(app_folder, "settings.yml"))
-
-    if settings.get("fpm_config_dir") == "/etc/php/7.0/fpm":
-        settings["fpm_config_dir"] = "/etc/php/7.3/fpm"
-    if settings.get("fpm_service") == "php7.0-fpm":
-        settings["fpm_service"] = "php7.3-fpm"
-    if settings.get("phpversion") == "7.0":
-        settings["phpversion"] = "7.3"
-
-    # We delete these checksums otherwise the file will appear as manually modified
-    list_to_remove = ["checksum__etc_php_7.0_fpm_pool", "checksum__etc_nginx_conf.d"]
-    settings = {
-        k: v
-        for k, v in settings.items()
-        if not any(k.startswith(to_remove) for to_remove in list_to_remove)
-    }
-
-    write_to_yaml(app_folder + "/settings.yml", settings)
-
-
-def _patch_legacy_helpers(app_folder):
-
-    files_to_patch = []
-    files_to_patch.extend(glob.glob("%s/scripts/*" % app_folder))
-    files_to_patch.extend(glob.glob("%s/scripts/.*" % app_folder))
-
-    stuff_to_replace = {
-        # Replace
-        #    sudo yunohost app initdb $db_user -p $db_pwd
-        # by
-        #    ynh_mysql_setup_db --db_user=$db_user --db_name=$db_user --db_pwd=$db_pwd
-        "yunohost app initdb": {
-            "pattern": r"(sudo )?yunohost app initdb \"?(\$\{?\w+\}?)\"?\s+-p\s\"?(\$\{?\w+\}?)\"?",
-            "replace": r"ynh_mysql_setup_db --db_user=\2 --db_name=\2 --db_pwd=\3",
-            "important": True,
-        },
-        # Replace
-        #    sudo yunohost app checkport whaterver
-        # by
-        #    ynh_port_available whatever
-        "yunohost app checkport": {
-            "pattern": r"(sudo )?yunohost app checkport",
-            "replace": r"ynh_port_available",
-            "important": True,
-        },
-        # We can't migrate easily port-available
-        # .. but at the time of writing this code, only two non-working apps are using it.
-        "yunohost tools port-available": {"important": True},
-        # Replace
-        #    yunohost app checkurl "${domain}${path_url}" -a "${app}"
-        # by
-        #    ynh_webpath_register --app=${app} --domain=${domain} --path_url=${path_url}
-        "yunohost app checkurl": {
-            "pattern": r"(sudo )?yunohost app checkurl \"?(\$\{?\w+\}?)\/?(\$\{?\w+\}?)\"?\s+-a\s\"?(\$\{?\w+\}?)\"?",
-            "replace": r"ynh_webpath_register --app=\4 --domain=\2 --path_url=\3",
-            "important": True,
-        },
-        # Remove
-        #    Automatic diagnosis data from YunoHost
-        #    __PRE_TAG1__$(yunohost tools diagnosis | ...)__PRE_TAG2__"
-        #
-        "yunohost tools diagnosis": {
-            "pattern": r"(Automatic diagnosis data from YunoHost( *\n)*)? *(__\w+__)? *\$\(yunohost tools diagnosis.*\)(__\w+__)?",
-            "replace": r"",
-            "important": False,
-        },
-        # Old $1, $2 in backup/restore scripts...
-        "app=$2": {
-            "only_for": ["scripts/backup", "scripts/restore"],
-            "pattern": r"app=\$2",
-            "replace": r"app=$YNH_APP_INSTANCE_NAME",
-            "important": True,
-        },
-        # Old $1, $2 in backup/restore scripts...
-        "backup_dir=$1": {
-            "only_for": ["scripts/backup", "scripts/restore"],
-            "pattern": r"backup_dir=\$1",
-            "replace": r"backup_dir=.",
-            "important": True,
-        },
-        # Old $1, $2 in backup/restore scripts...
-        "restore_dir=$1": {
-            "only_for": ["scripts/restore"],
-            "pattern": r"restore_dir=\$1",
-            "replace": r"restore_dir=.",
-            "important": True,
-        },
-        # Old $1, $2 in install scripts...
-        # We ain't patching that shit because it ain't trivial to patch all args...
-        "domain=$1": {"only_for": ["scripts/install"], "important": True},
-    }
-
-    for helper, infos in stuff_to_replace.items():
-        infos["pattern"] = (
-            re.compile(infos["pattern"]) if infos.get("pattern") else None
-        )
-        infos["replace"] = infos.get("replace")
-
-    for filename in files_to_patch:
-
-        # Ignore non-regular files
-        if not os.path.isfile(filename):
-            continue
-
-        try:
-            content = read_file(filename)
-        except MoulinetteError:
-            continue
-
-        replaced_stuff = False
-        show_warning = False
-
-        for helper, infos in stuff_to_replace.items():
-
-            # Ignore if not relevant for this file
-            if infos.get("only_for") and not any(
-                filename.endswith(f) for f in infos["only_for"]
-            ):
-                continue
-
-            # If helper is used, attempt to patch the file
-            if helper in content and infos["pattern"]:
-                content = infos["pattern"].sub(infos["replace"], content)
-                replaced_stuff = True
-                if infos["important"]:
-                    show_warning = True
-
-            # If the helper is *still* in the content, it means that we
-            # couldn't patch the deprecated helper in the previous lines.  In
-            # that case, abort the install or whichever step is performed
-            if helper in content and infos["important"]:
-                raise YunohostValidationError(
-                    "This app is likely pretty old and uses deprecated / outdated helpers that can't be migrated easily. It can't be installed anymore.",
-                    raw_msg=True,
-                )
-
-        if replaced_stuff:
-
-            # Check the app do load the helper
-            # If it doesn't, add the instruction ourselve (making sure it's after the #!/bin/bash if it's there...
-            if filename.split("/")[-1] in [
-                "install",
-                "remove",
-                "upgrade",
-                "backup",
-                "restore",
-            ]:
-                source_helpers = "source /usr/share/yunohost/helpers"
-                if source_helpers not in content:
-                    content.replace("#!/bin/bash", "#!/bin/bash\n" + source_helpers)
-                if source_helpers not in content:
-                    content = source_helpers + "\n" + content
-
-            # Actually write the new content in the file
-            write_to_file(filename, content)
-
-        if show_warning:
-            # And complain about those damn deprecated helpers
-            logger.error(
-                r"/!\ Packagers ! This app uses a very old deprecated helpers ... Yunohost automatically patched the helpers to use the new recommended practice, but please do consider fixing the upstream code right now ..."
-            )
diff --git a/src/yunohost/backup.py b/src/yunohost/backup.py
index a47fba5f7..b650cb3da 100644
--- a/src/yunohost/backup.py
+++ b/src/yunohost/backup.py
@@ -49,10 +49,6 @@ from yunohost.app import (
     app_info,
     _is_installed,
     _make_environment_for_app_script,
-    _patch_legacy_helpers,
-    _patch_legacy_php_versions,
-    _patch_legacy_php_versions_in_settings,
-    LEGACY_PHP_VERSION_REPLACEMENTS,
     _make_tmp_workdir_for_app,
 )
 from yunohost.hook import (
@@ -1190,6 +1186,7 @@ class RestoreManager:
         """
         Apply dirty patch to redirect php5 and php7.0 files to php7.3
         """
+        from yunohost.utils.legacy import LEGACY_PHP_VERSION_REPLACEMENTS
 
         backup_csv = os.path.join(self.work_dir, "backup.csv")
 
@@ -1351,6 +1348,7 @@ class RestoreManager:
         app_instance_name -- (string) The app name to restore (no app with this
                              name should be already install)
         """
+        from yunohost.utils.legacy import _patch_legacy_php_versions, _patch_legacy_php_versions_in_settings, _patch_legacy_helpers
         from yunohost.user import user_group_list
         from yunohost.permission import (
             permission_create,
diff --git a/src/yunohost/data_migrations/0016_php70_to_php73_pools.py b/src/yunohost/data_migrations/0016_php70_to_php73_pools.py
index 6b424f211..fed96c9c8 100644
--- a/src/yunohost/data_migrations/0016_php70_to_php73_pools.py
+++ b/src/yunohost/data_migrations/0016_php70_to_php73_pools.py
@@ -4,7 +4,8 @@ from shutil import copy2
 
 from moulinette.utils.log import getActionLogger
 
-from yunohost.app import _is_installed, _patch_legacy_php_versions_in_settings
+from yunohost.app import _is_installed
+from yunohost.utils.legacy import _patch_legacy_php_versions_in_settings
 from yunohost.tools import Migration
 from yunohost.service import _run_service_command
 
diff --git a/src/yunohost/utils/legacy.py b/src/yunohost/utils/legacy.py
index eb92dd71f..7ae98bed8 100644
--- a/src/yunohost/utils/legacy.py
+++ b/src/yunohost/utils/legacy.py
@@ -1,7 +1,10 @@
 import os
+import re
+import glob
 from moulinette import m18n
+from moulinette.core import MoulinetteError
 from moulinette.utils.log import getActionLogger
-from moulinette.utils.filesystem import write_to_json, read_yaml
+from moulinette.utils.filesystem import read_file, write_to_file, write_to_json, write_to_yaml, read_yaml
 
 from yunohost.user import user_list
 from yunohost.app import (
@@ -14,6 +17,8 @@ from yunohost.permission import (
     user_permission_update,
     permission_sync_to_user,
 )
+from yunohost.utils.error import YunohostValidationError
+
 
 logger = getActionLogger("yunohost.legacy")
 
@@ -237,3 +242,213 @@ def translate_legacy_rules_in_ssowant_conf_json_persistent():
     logger.warning(
         "YunoHost automatically translated some legacy rules in /etc/ssowat/conf.json.persistent to match the new permission system"
     )
+
+
+LEGACY_PHP_VERSION_REPLACEMENTS = [
+    ("/etc/php5", "/etc/php/7.3"),
+    ("/etc/php/7.0", "/etc/php/7.3"),
+    ("/var/run/php5-fpm", "/var/run/php/php7.3-fpm"),
+    ("/var/run/php/php7.0-fpm", "/var/run/php/php7.3-fpm"),
+    ("php5", "php7.3"),
+    ("php7.0", "php7.3"),
+    (
+        'phpversion="${phpversion:-7.0}"',
+        'phpversion="${phpversion:-7.3}"',
+    ),  # Many helpers like the composer ones use 7.0 by default ...
+    (
+        '"$phpversion" == "7.0"',
+        '$(bc <<< "$phpversion >= 7.3") -eq 1',
+    ),  # patch ynh_install_php to refuse installing/removing php <= 7.3
+]
+
+
+def _patch_legacy_php_versions(app_folder):
+
+    files_to_patch = []
+    files_to_patch.extend(glob.glob("%s/conf/*" % app_folder))
+    files_to_patch.extend(glob.glob("%s/scripts/*" % app_folder))
+    files_to_patch.extend(glob.glob("%s/scripts/*/*" % app_folder))
+    files_to_patch.extend(glob.glob("%s/scripts/.*" % app_folder))
+    files_to_patch.append("%s/manifest.json" % app_folder)
+    files_to_patch.append("%s/manifest.toml" % app_folder)
+
+    for filename in files_to_patch:
+
+        # Ignore non-regular files
+        if not os.path.isfile(filename):
+            continue
+
+        c = (
+            "sed -i "
+            + "".join(
+                "-e 's@{pattern}@{replace}@g' ".format(pattern=p, replace=r)
+                for p, r in LEGACY_PHP_VERSION_REPLACEMENTS
+            )
+            + "%s" % filename
+        )
+        os.system(c)
+
+
+def _patch_legacy_php_versions_in_settings(app_folder):
+
+    settings = read_yaml(os.path.join(app_folder, "settings.yml"))
+
+    if settings.get("fpm_config_dir") == "/etc/php/7.0/fpm":
+        settings["fpm_config_dir"] = "/etc/php/7.3/fpm"
+    if settings.get("fpm_service") == "php7.0-fpm":
+        settings["fpm_service"] = "php7.3-fpm"
+    if settings.get("phpversion") == "7.0":
+        settings["phpversion"] = "7.3"
+
+    # We delete these checksums otherwise the file will appear as manually modified
+    list_to_remove = ["checksum__etc_php_7.0_fpm_pool", "checksum__etc_nginx_conf.d"]
+    settings = {
+        k: v
+        for k, v in settings.items()
+        if not any(k.startswith(to_remove) for to_remove in list_to_remove)
+    }
+
+    write_to_yaml(app_folder + "/settings.yml", settings)
+
+
+def _patch_legacy_helpers(app_folder):
+
+    files_to_patch = []
+    files_to_patch.extend(glob.glob("%s/scripts/*" % app_folder))
+    files_to_patch.extend(glob.glob("%s/scripts/.*" % app_folder))
+
+    stuff_to_replace = {
+        # Replace
+        #    sudo yunohost app initdb $db_user -p $db_pwd
+        # by
+        #    ynh_mysql_setup_db --db_user=$db_user --db_name=$db_user --db_pwd=$db_pwd
+        "yunohost app initdb": {
+            "pattern": r"(sudo )?yunohost app initdb \"?(\$\{?\w+\}?)\"?\s+-p\s\"?(\$\{?\w+\}?)\"?",
+            "replace": r"ynh_mysql_setup_db --db_user=\2 --db_name=\2 --db_pwd=\3",
+            "important": True,
+        },
+        # Replace
+        #    sudo yunohost app checkport whaterver
+        # by
+        #    ynh_port_available whatever
+        "yunohost app checkport": {
+            "pattern": r"(sudo )?yunohost app checkport",
+            "replace": r"ynh_port_available",
+            "important": True,
+        },
+        # We can't migrate easily port-available
+        # .. but at the time of writing this code, only two non-working apps are using it.
+        "yunohost tools port-available": {"important": True},
+        # Replace
+        #    yunohost app checkurl "${domain}${path_url}" -a "${app}"
+        # by
+        #    ynh_webpath_register --app=${app} --domain=${domain} --path_url=${path_url}
+        "yunohost app checkurl": {
+            "pattern": r"(sudo )?yunohost app checkurl \"?(\$\{?\w+\}?)\/?(\$\{?\w+\}?)\"?\s+-a\s\"?(\$\{?\w+\}?)\"?",
+            "replace": r"ynh_webpath_register --app=\4 --domain=\2 --path_url=\3",
+            "important": True,
+        },
+        # Remove
+        #    Automatic diagnosis data from YunoHost
+        #    __PRE_TAG1__$(yunohost tools diagnosis | ...)__PRE_TAG2__"
+        #
+        "yunohost tools diagnosis": {
+            "pattern": r"(Automatic diagnosis data from YunoHost( *\n)*)? *(__\w+__)? *\$\(yunohost tools diagnosis.*\)(__\w+__)?",
+            "replace": r"",
+            "important": False,
+        },
+        # Old $1, $2 in backup/restore scripts...
+        "app=$2": {
+            "only_for": ["scripts/backup", "scripts/restore"],
+            "pattern": r"app=\$2",
+            "replace": r"app=$YNH_APP_INSTANCE_NAME",
+            "important": True,
+        },
+        # Old $1, $2 in backup/restore scripts...
+        "backup_dir=$1": {
+            "only_for": ["scripts/backup", "scripts/restore"],
+            "pattern": r"backup_dir=\$1",
+            "replace": r"backup_dir=.",
+            "important": True,
+        },
+        # Old $1, $2 in backup/restore scripts...
+        "restore_dir=$1": {
+            "only_for": ["scripts/restore"],
+            "pattern": r"restore_dir=\$1",
+            "replace": r"restore_dir=.",
+            "important": True,
+        },
+        # Old $1, $2 in install scripts...
+        # We ain't patching that shit because it ain't trivial to patch all args...
+        "domain=$1": {"only_for": ["scripts/install"], "important": True},
+    }
+
+    for helper, infos in stuff_to_replace.items():
+        infos["pattern"] = (
+            re.compile(infos["pattern"]) if infos.get("pattern") else None
+        )
+        infos["replace"] = infos.get("replace")
+
+    for filename in files_to_patch:
+
+        # Ignore non-regular files
+        if not os.path.isfile(filename):
+            continue
+
+        try:
+            content = read_file(filename)
+        except MoulinetteError:
+            continue
+
+        replaced_stuff = False
+        show_warning = False
+
+        for helper, infos in stuff_to_replace.items():
+
+            # Ignore if not relevant for this file
+            if infos.get("only_for") and not any(
+                filename.endswith(f) for f in infos["only_for"]
+            ):
+                continue
+
+            # If helper is used, attempt to patch the file
+            if helper in content and infos["pattern"]:
+                content = infos["pattern"].sub(infos["replace"], content)
+                replaced_stuff = True
+                if infos["important"]:
+                    show_warning = True
+
+            # If the helper is *still* in the content, it means that we
+            # couldn't patch the deprecated helper in the previous lines.  In
+            # that case, abort the install or whichever step is performed
+            if helper in content and infos["important"]:
+                raise YunohostValidationError(
+                    "This app is likely pretty old and uses deprecated / outdated helpers that can't be migrated easily. It can't be installed anymore.",
+                    raw_msg=True,
+                )
+
+        if replaced_stuff:
+
+            # Check the app do load the helper
+            # If it doesn't, add the instruction ourselve (making sure it's after the #!/bin/bash if it's there...
+            if filename.split("/")[-1] in [
+                "install",
+                "remove",
+                "upgrade",
+                "backup",
+                "restore",
+            ]:
+                source_helpers = "source /usr/share/yunohost/helpers"
+                if source_helpers not in content:
+                    content.replace("#!/bin/bash", "#!/bin/bash\n" + source_helpers)
+                if source_helpers not in content:
+                    content = source_helpers + "\n" + content
+
+            # Actually write the new content in the file
+            write_to_file(filename, content)
+
+        if show_warning:
+            # And complain about those damn deprecated helpers
+            logger.error(
+                r"/!\ Packagers ! This app uses a very old deprecated helpers ... Yunohost automatically patched the helpers to use the new recommended practice, but please do consider fixing the upstream code right now ..."
+            )