diff --git a/scripts/_common.sh b/scripts/_common.sh
index ebffb0e..bd77d63 100644
--- a/scripts/_common.sh
+++ b/scripts/_common.sh
@@ -1,3 +1,4 @@
+#!/bin/bash
 
 #=================================================
 # COMMON VARIABLES
diff --git a/scripts/_ynh_mysql_connect_as.sh b/scripts/_ynh_mysql_connect_as.sh
new file mode 100644
index 0000000..0176800
--- /dev/null
+++ b/scripts/_ynh_mysql_connect_as.sh
@@ -0,0 +1,34 @@
+#!/bin/bash
+
+# Open a connection as a user
+#
+# example: ynh_mysql_connect_as --user="user" --password="pass" <<< "UPDATE ...;"
+# example: ynh_mysql_connect_as --user="user" --password="pass" --default_character_set="utf8mb4" < /path/to/file.sql
+#
+# usage: ynh_mysql_connect_as --user=user --password=password [--database=database] [--default_character_set=character-set]
+# | arg: -u, --user=                        - the user name to connect as
+# | arg: -p, --password=                    - the user password
+# | arg: -d, --database=                    - the database to connect to
+# | arg: -c, --default_character_set=       - the charset to use
+#
+# Requires YunoHost version 2.2.4 or higher.
+ynh_mysql_connect_as() {
+    # Declare an array to define the options of this helper.
+    local legacy_args=updc
+    local -A args_array=( [u]=user= [p]=password= [d]=database= [c]=default_character_set= )
+    local user
+    local password
+    local database
+    local default_character_set
+    # Manage arguments with getopts
+    ynh_handle_getopts_args "$@"
+    database="${database:-}"
+    default_character_set="${default_character_set:-}"
+
+    if [ -n "$default_character_set" ]
+    then
+        default_character_set="--default-character-set=$default_character_set"
+    fi
+
+    mysql --user="$user" --password="$password" "$default_character_set" --batch "$database"
+}
\ No newline at end of file
diff --git a/scripts/_ynh_mysql_dump_db.sh b/scripts/_ynh_mysql_dump_db.sh
new file mode 100644
index 0000000..743c96a
--- /dev/null
+++ b/scripts/_ynh_mysql_dump_db.sh
@@ -0,0 +1,29 @@
+#!/bin/bash
+
+# Dump a database
+#
+# example: ynh_mysql_dump_db --database=roundcube --default_character_set="utf8mb4" > ./dump.sql
+#
+# usage: ynh_mysql_dump_db --database=database
+# | arg: -d, --database=    - the database name to dump
+# | arg: -c, --default_character_set=       - the charset to use
+# | ret: the mysqldump output
+#
+# Requires YunoHost version 2.2.4 or higher.
+ynh_mysql_dump_db() {
+    # Declare an array to define the options of this helper.
+    local legacy_args=dc
+    local -A args_array=( [d]=database= [c]=default_character_set= )
+    local database
+    local default_character_set
+    # Manage arguments with getopts
+    ynh_handle_getopts_args "$@"
+    default_character_set="${default_character_set:-}"
+
+    if [ -n "$default_character_set" ]
+    then
+        default_character_set="--default-character-set=$default_character_set"
+    fi
+
+    mysqldump --user="root" --password="$(cat $MYSQL_ROOT_PWD_FILE)" --single-transaction --skip-dump-date "$default_character_set" "$database"
+}
\ No newline at end of file
diff --git a/scripts/backup b/scripts/backup
index 7ed3c7f..6a115ba 100755
--- a/scripts/backup
+++ b/scripts/backup
@@ -8,6 +8,7 @@
 
 source ../settings/scripts/_common.sh
 source /usr/share/yunohost/helpers
+source ../settings/scripts/_ynh_mysql_dump_db.sh
 
 #=================================================
 # MANAGE SCRIPT FAILURE
@@ -56,7 +57,7 @@ ynh_backup --src_path="/etc/php/$phpversion/fpm/pool.d/$app.conf"
 #=================================================
 ynh_print_info --message="Backing up the MySQL database..."
 
-ynh_mysql_dump_db --database="$db_name" > db.sql
+ynh_mysql_dump_db --database="$db_name" --default_character_set="utf8mb4" > db.sql
 
 #=================================================
 # SPECIFIC BACKUP
diff --git a/scripts/install b/scripts/install
index 983dd65..8d444fb 100755
--- a/scripts/install
+++ b/scripts/install
@@ -8,6 +8,7 @@
 
 source _common.sh
 source /usr/share/yunohost/helpers
+source _ynh_mysql_connect_as.sh
 
 #=================================================
 # MANAGE SCRIPT FAILURE
@@ -250,7 +251,7 @@ ynh_replace_string --match_string="'overwrite.cli.url' => 'http://localhost'," -
 #=================================================
 
 # Set the user as admin
-ynh_mysql_connect_as --user=$db_name --password="$db_pwd" --database=$db_name \
+ynh_mysql_connect_as --user=$db_name --password="$db_pwd" --database=$db_name --default_character_set="utf8mb4" \
     <<< "INSERT INTO oc_group_user VALUES ('admin','$admin');"
 # And delete admin user
 exec_occ user:delete admin
diff --git a/scripts/restore b/scripts/restore
index 44f8384..5dea17e 100755
--- a/scripts/restore
+++ b/scripts/restore
@@ -8,6 +8,7 @@
 
 source ../settings/scripts/_common.sh
 source /usr/share/yunohost/helpers
+source ../settings/scripts/_ynh_mysql_connect_as.sh
 
 #=================================================
 # MANAGE SCRIPT FAILURE
@@ -73,7 +74,10 @@ ynh_script_progression --message="Restoring the MySQL database..." --weight=9
 
 db_pwd=$(ynh_app_setting_get --app=$app --key=mysqlpwd)
 ynh_mysql_setup_db --db_user=$db_name --db_name=$db_name --db_pwd=$db_pwd
-ynh_mysql_connect_as --user=$db_name --password=$db_pwd --database=$db_name < ./db.sql
+ynh_mysql_connect_as --user=$db_name --password="$db_pwd" --database=$db_name \
+    <<< "ALTER DATABASE $db_name CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;"
+
+ynh_mysql_connect_as --user=$db_name --password=$db_pwd --database=$db_name --default_character_set="utf8mb4" < ./db.sql
 
 #=================================================
 # RECREATE THE DEDICATED USER
diff --git a/scripts/upgrade b/scripts/upgrade
index 0569ce4..7ab6a0f 100755
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -221,7 +221,9 @@ then
     # Print the current version number of Nextcloud
     exec_occ -V
 
-    exec_occ db:convert-mysql-charset
+    if [ "$(exec_occ config:system:get mysql.utf8mb4)" != "true" ]; then
+        exec_occ db:convert-mysql-charset
+    fi
 
     # Upgrade may fail if this app is enabled
     # Take all apps enabled, and check if mail is one of them