diff --git a/docker/Dockerfile b/docker/Dockerfile
index f656b3a3..8bcb05ce 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -28,7 +28,7 @@ COPY --from=composer /app/composer.lock /app/
 RUN find /app/storage/ -type f -not -name VERSION -exec rm {} \;
 
 # Build the PHP container
-FROM php:7-fpm-alpine
+FROM php:8-fpm-alpine
 WORKDIR /var/www
 RUN apk add --no-cache icu-dev && \
     docker-php-ext-install intl pdo_mysql
diff --git a/docker/dev/Dockerfile b/docker/dev/Dockerfile
index 98fb3177..cc89b9f4 100644
--- a/docker/dev/Dockerfile
+++ b/docker/dev/Dockerfile
@@ -1,11 +1,11 @@
 # Engelsystem PHP FPM development image including Xdebug
-FROM php:7-fpm-alpine AS es_php_fpm
+FROM php:8-fpm-alpine AS es_php_fpm
 WORKDIR /var/www
 RUN apk add --no-cache icu-dev $PHPIZE_DEPS && \
     pecl install pcov xdebug && \
     docker-php-ext-install intl pdo_mysql && \
     docker-php-ext-enable pcov xdebug
-RUN  echo -e "xdebug.remote_enable=1\nxdebug.remote_connect_back=1\n" >> /usr/local/etc/php/conf.d/xdebug.ini
+RUN echo -e "xdebug.mode=debug\nxdebug.discover_client_host=1\n" >> /usr/local/etc/php/conf.d/xdebug.ini
 
 ENV TRUSTED_PROXIES 10.0.0.0/8,::ffff:10.0.0.0/8,\
                     127.0.0.0/8,::ffff:127.0.0.0/8,\
diff --git a/docker/nginx/nginx.conf b/docker/nginx/nginx.conf
index 63e934bc..c2f52aef 100644
--- a/docker/nginx/nginx.conf
+++ b/docker/nginx/nginx.conf
@@ -11,6 +11,9 @@ http {
   scgi_temp_path        /tmp/scgi_temp;
   uwsgi_temp_path       /tmp/uwsgi_temp;
 
+  fastcgi_buffers       16 16k;
+  fastcgi_buffer_size   32k;
+
   map $http_x_forwarded_proto $forwarded_proto {
     default $http_x_forwarded_proto;
     https   https;
diff --git a/includes/pages/user_shifts.php b/includes/pages/user_shifts.php
index bbaeb708..be43b67e 100644
--- a/includes/pages/user_shifts.php
+++ b/includes/pages/user_shifts.php
@@ -115,12 +115,15 @@ function load_rooms()
  */
 function load_days()
 {
-    $days = DB::select('
-        SELECT DISTINCT DATE(FROM_UNIXTIME(`start`)) AS `id`, DATE(FROM_UNIXTIME(`start`)) AS `name`
-        FROM `Shifts`
-        ORDER BY `id`, `name`
-    ');
-    $days = array_map('array_shift', $days);
+    $days = (new Collection(DB::select(
+        '
+                SELECT DISTINCT DATE(FROM_UNIXTIME(`start`)) AS `id`, DATE(FROM_UNIXTIME(`start`)) AS `name`
+                FROM `Shifts`
+                ORDER BY `id`, `name`
+            '
+    )))
+        ->pluck('id')
+        ->toArray();
 
     if (empty($days)) {
         error(__('The administration has not configured any shifts yet.'));