diff --git a/manifest.json b/manifest.json
index e168c92..0fd0b35 100644
--- a/manifest.json
+++ b/manifest.json
@@ -7,15 +7,15 @@
 		"fr": "Un méta-moteur de recherche respectueux de la vie privée et bidouillable", 
 		"de": "Eine Meta-Suchmaschine, die den Privatsphäre wahrt und 'hackable' ist."
 	},
-	"version": "0.13.1-1",
+	"version": "0.13.1~ynh1",
 	"url": "https://asciimoo.github.io/searx/",
-	"license": "AGPLv3",
+	"license": "AGPL-3.0-or-later",
 	"maintainer": {
 		"name": "opi",
 		"email": "opi@zeropi.net"
 	},
 	"requirements": {
-        "yunohost": ">= 2.7.2"
+        "yunohost": ">= 2.7.12"
 	},
 	"multi_instance": false,
 	"services": [
diff --git a/scripts/backup b/scripts/backup
index 96afb05..9c08491 100755
--- a/scripts/backup
+++ b/scripts/backup
@@ -21,6 +21,13 @@ set -eu
 # source _common.sh
 source /usr/share/yunohost/helpers
 
+#=================================================
+# MANAGE SCRIPT FAILURE
+#=================================================
+
+# Exit if an error occurs during the execution of the script
+ynh_abort_if_errors
+
 #=================================================
 # LOAD SETTINGS
 #=================================================
diff --git a/scripts/install b/scripts/install
index b068236..1341f5f 100644
--- a/scripts/install
+++ b/scripts/install
@@ -55,7 +55,7 @@ ynh_app_setting_set $app is_public $is_public
 # INSTALL DEPENDENCIES
 #=================================================
 
-ynh_install_app_dependencies git build-essential libxslt-dev python-dev python-virtualenv virtualenv python-pybabel zlib1g-dev libffi-dev libssl-dev python-lxml uwsgi uwsgi-plugin-python
+ynh_install_app_dependencies git build-essential libxslt-dev python-dev python-virtualenv virtualenv zlib1g-dev libffi-dev libssl-dev uwsgi uwsgi-plugin-python
 
 #=================================================
 # NGINX CONFIGURATION
@@ -93,8 +93,17 @@ ynh_setup_source "$final_path"
 # INSTALL SEARX IN A VIRTUALENV
 #=================================================
 
-virtualenv --system-site-packages "$final_path"
-bash -c "source $final_path/bin/activate && pip install -U pip setuptools && pip install --requirement $final_path/requirements-ynh.txt"
+virtualenv "$final_path"
+#run source in a 'sub shell'
+(
+	set +o nounset
+	source "$final_path/bin/activate"
+	set -o nounset
+	pip install --upgrade pip
+	pip install --upgrade setuptools
+	pip install --requirement "$final_path/requirements-ynh.txt"
+	pip install lxml babel
+)
 
 #=================================================
 # CONFIGURE SEARX
diff --git a/scripts/restore b/scripts/restore
index ddbe66f..442b572 100755
--- a/scripts/restore
+++ b/scripts/restore
@@ -21,6 +21,13 @@ set -eu
 # source _common.sh
 source /usr/share/yunohost/helpers
 
+#=================================================
+# MANAGE SCRIPT FAILURE
+#=================================================
+
+# Exit if an error occurs during the execution of the script
+ynh_abort_if_errors
+
 #=================================================
 # LOAD SETTINGS
 #=================================================
diff --git a/scripts/upgrade b/scripts/upgrade
index c6fca67..701caac 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -58,6 +58,12 @@ path_url=$(ynh_normalize_url_path $path_url)
 
 #=================================================
 # STANDARD UPGRADE STEPS
+#=================================================
+# INSTALL DEPENDENCIES
+#=================================================
+
+ynh_install_app_dependencies git build-essential libxslt-dev python-dev python-virtualenv virtualenv zlib1g-dev libffi-dev libssl-dev uwsgi uwsgi-plugin-python
+
 #=================================================
 # DOWNLOAD, CHECK AND UNPACK SOURCE
 #=================================================
@@ -97,8 +103,19 @@ ynh_system_user_create $app
 #=================================================
 
 rm -r $final_path/lib/python2.7/site-packages/{pip,setuptools} $final_path/lib/python2.7/site-packages/setuptools-* $final_path/lib/python2.7/site-packages/pip-*
-virtualenv --system-site-packages "$final_path"
-bash -c "source $final_path/bin/activate && pip install -U pip setuptools && pip install --requirement $final_path/requirements-ynh.txt --upgrade"
+virtualenv "$final_path"
+
+#run source in a 'sub shell'
+(
+	set +o nounset
+	source "$final_path/bin/activate"
+	set -o nounset
+	pip install --upgrade pip
+	pip install --upgrade setuptools
+	pip install --requirement "$final_path/requirements-ynh.txt"
+	pip install lxml babel
+)
+
 
 #=================================================
 # CONFIGURE SEARX