diff --git a/README.md b/README.md
index 3390f01..3e2b8dc 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,7 @@ If you don't have YunoHost, please consult [the guide](https://yunohost.org/#/in
 
 CryptPad is a collaboration suite that is end-to-end-encrypted and open-source. It is built to enable collaboration, synchronizing changes to documents in real time. Because all data is encrypted, the service and its administrators have no way of seeing the content being edited and stored.
 
-**Shipped version:** 5.2.1~ynh3
+**Shipped version:** 5.2.1~ynh4
 
 **Demo:** https://cryptpad.fr/
 
diff --git a/README_fr.md b/README_fr.md
index a02aa99..f8f6e45 100644
--- a/README_fr.md
+++ b/README_fr.md
@@ -18,7 +18,7 @@ Si vous n’avez pas YunoHost, regardez [ici](https://yunohost.org/#/install) po
 
 CryptPad est une suite de collaboration chiffrée de bout en bout et open source. Il est conçu pour permettre la collaboration, en synchronisant les modifications apportées aux documents en temps réel. Étant donné que toutes les données sont chiffrées, le service et ses administrateurs n'ont aucun moyen de voir le contenu modifié et stocké. 
 
-**Version incluse :** 5.2.1~ynh3
+**Version incluse :** 5.2.1~ynh4
 
 **Démo :** https://cryptpad.fr/
 
diff --git a/manifest.json b/manifest.json
index fd41b14..7d68ecc 100644
--- a/manifest.json
+++ b/manifest.json
@@ -6,7 +6,7 @@
         "en": "Zero Knowledge realtime collaborative office suite",
         "fr": "Suite bureautique chiffrée pour la collaboration en temps réel"
     },
-    "version": "5.2.1~ynh3",
+    "version": "5.2.1~ynh4",
     "url": "https://cryptpad.fr/",
     "upstream": {
         "license": "AGPL-3.0-only",
diff --git a/scripts/upgrade b/scripts/upgrade
index 2d0e277..39afa10 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -118,12 +118,15 @@ if [[ $domain == *".local" ]]; then
 	sandboxdomain=sandbox-$domain
 fi
 
-ynh_script_progression --message="Setting up sandobx domain : $sandboxdomain" --weight=1
+ynh_script_progression --message="Setting up sandobx domain: $sandboxdomain" --weight=1
 
 # We don't test that in CI
 if ! [ ${PACKAGE_CHECK_EXEC:-0} -eq 1 ]; then
-	yunohost domain add $sandboxdomain
-	yunohost domain config set $sandboxdomain -a "mail_in=0&mail_out=0"
+	# If sandboxdomain doesn't exist, create it
+	if [ -z "$sandboxdomain" ]; then
+		yunohost domain add $sandboxdomain
+		yunohost domain config set $sandboxdomain -a "mail_in=0&mail_out=0"
+	fi
 fi
 
 #=================================================