diff --git a/eventarc/generic/Dockerfile b/eventarc/generic/Dockerfile
index 097535fc84..80846818ad 100644
--- a/eventarc/generic/Dockerfile
+++ b/eventarc/generic/Dockerfile
@@ -16,7 +16,7 @@
 
 # Use the official PHP image.
 # https://hub.docker.com/_/php
-FROM php:8.1-apache
+FROM php:8.4-apache
 
 # Configure PHP for Cloud Run.
 # Precompile PHP code with opcache.
@@ -40,6 +40,9 @@ RUN set -ex; \
 WORKDIR /var/www/html
 COPY . ./
 
+# Ensure the webserver has permissions to execute index.php
+RUN chown -R www-data:www-data /var/www/html
+
 # Use the PORT environment variable in Apache configuration files.
 # https://cloud.google.com/run/docs/reference/container-contract#port
 RUN sed -i 's/80/${PORT}/g' /etc/apache2/sites-available/000-default.conf /etc/apache2/ports.conf