diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3b5a083..136e80d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,10 @@
 ### Minor changes
 
 * **2026-10-09**
+  * Fix the container start when the mounted directory belongs to an ID used by a system account of the image (e.g. 998 for a `gitlab-runner` user): the commands were run with this account (no home directory, no sudo) instead of the `docker` user
+  * Fix `DOCKER_USER` set to an ID used by a system account of the image (`usermod: UID already exists`)
+  * Fix `php` run by a user that cannot use sudo (e.g. `sudo -u www-data php ...`): sudo password errors, and failure when a `PHP_*` variable had changed
+  * Fix PHP warnings (e.g. an extension that cannot be loaded) breaking the container start: they were written in `generated_conf.ini`, in the crontab and in the startup commands
   * Fix the fpm variant stop: PHP-FPM is now stopped gracefully (`SIGQUIT`: running requests are completed) and port 9000 is exposed
   * Fix stop requests sent while the apache or fpm container is starting: the stop signal (`SIGWINCH` / `SIGQUIT`) was ignored by the entrypoint and the container was killed after the stop timeout
   * Fix Apache modules listed in the documentation but rejected by `APACHE_EXTENSION_*`: `brotli`, `cern_meta`, `imagemap`, `md`, `proxy_hcheck`, `proxy_uwsgi`, `socache_redis`
diff --git a/README.md b/README.md
index 684615e..0054d37 100644
--- a/README.md
+++ b/README.md
@@ -423,6 +423,10 @@ working directory (`/var/www/html` for Apache/PHP-FPM, or `/usr/src/app` for CLI
 you want to run commands as this user. So it will **dynamically change the ID of the docker user** to match the ID of
 the current working directory user.
 
+If this ID is already used by a system account of the image (e.g. `998`, used by `systemd-network` in the image and
+often by the `gitlab-runner` user on CI hosts), this system account is moved to another ID: the commands are still run
+by the `docker` user.
+
 Furthermore, the image is changing the Apache default user/group to be `docker/docker` (instead if `www-data/www-data`).
 So Apache will run with the same rights as the user on your host.
 
diff --git a/tests-suite/assets/php-startup-warning.ini b/tests-suite/assets/php-startup-warning.ini
new file mode 100644
index 0000000..d242910
--- /dev/null
+++ b/tests-suite/assets/php-startup-warning.ini
@@ -0,0 +1,2 @@
+; Loading an extension that does not exist makes PHP display a startup warning
+extension=does_not_exist
diff --git a/tests-suite/tool-startup-command.sh b/tests-suite/tool-startup-command.sh
index bce45d7..ec6f615 100755
--- a/tests-suite/tool-startup-command.sh
+++ b/tests-suite/tool-startup-command.sh
@@ -25,3 +25,13 @@ test_withFile() {
     "${REPO}:${TAG_PREFIX}${PHP_VERSION}-${BRANCH}-slim-${BRANCH_VARIANT}${ARCH_SUFFIX}" php -m 2>/dev/null | grep -q "startup.sh executed"
   assert_equals "0" "$?"
 }
+############################################################
+## Tests that a PHP startup warning does not prevent the container from starting
+############################################################
+test_phpStartupWarning() {
+  RESULT="$(docker run ${RUN_OPTIONS} --rm -e STARTUP_COMMAND_1="echo startup-ok" \
+    -v "${SCRIPT_DIR}/assets/php-startup-warning.ini":"/etc/php/${PHP_VERSION}/cli/conf.d/99-startup-warning.ini" \
+    "${REPO}:${TAG_PREFIX}${PHP_VERSION}-${BRANCH}-slim-${BRANCH_VARIANT}${ARCH_SUFFIX}" sleep 1 2>/dev/null)"
+  assert_equals "0" "$?" "Docker run failed"
+  assert_equals "startup-ok" "$RESULT"
+}
diff --git a/tests-suite/users-rights.sh b/tests-suite/users-rights.sh
index abdfc61..aa80845 100755
--- a/tests-suite/users-rights.sh
+++ b/tests-suite/users-rights.sh
@@ -36,7 +36,7 @@ test_defaultUserCanWriteOnStdoutAndStderr() {
 ############################################################
 ## It's also works for users with existing IDs in the container
 ############################################################
-test_defaultUserCanWriteOnStdoutAndStderr() {
+test_defaultUserCanBeAnExistingUser() {
   mkdir -p "${TMP_DIR}/user33"
   cat << EOF > "${TMP_DIR}/user33/composer.json"
   {
@@ -58,6 +58,32 @@ EOF
 }
 
 
+############################################################
+## The system accounts of the image (systemd-network, polkitd...)
+## do not take the place of the default user when they have the
+## ID of the mounted directory (e.g. 998 for gitlab-runner)
+############################################################
+test_defaultUserTakesUidOfSystemAccount() {
+  mkdir -p "${TMP_DIR}/user998"
+  docker run ${RUN_OPTIONS} --rm -v /tmp:/tmp busybox chown 998:998 "${TMP_DIR}/user998" > /dev/null 2>&1
+  RESULT="$(docker run ${RUN_OPTIONS} --rm -v "${TMP_DIR}/user998":"${CONTAINER_CWD}" -e STARTUP_COMMAND_1='touch ~/.startup_done' \
+    "${REPO}:${TAG_PREFIX}${PHP_VERSION}-${BRANCH}-slim-${BRANCH_VARIANT}${ARCH_SUFFIX}" \
+    bash -c 'echo "$(id -un):$(id -ur)"')"
+  assert_equals "0" "$?" "Docker run failed"
+  assert_equals "docker:998" "${RESULT}" "Default user mismatch with a mounted directory owned by a system account ID"
+}
+
+############################################################
+## Users that cannot use sudo can run PHP, even when a PHP_*
+## environment variable has changed
+############################################################
+test_userWithoutSudoCanRunPhp() {
+  RESULT="$(docker run ${RUN_OPTIONS} --rm "${REPO}:${TAG_PREFIX}${PHP_VERSION}-${BRANCH}-slim-${BRANCH_VARIANT}${ARCH_SUFFIX}" \
+    sudo -E -u www-data PHP_INI_MEMORY_LIMIT=1G php -r 'echo "OK";' 2>&1)"
+  assert_equals "0" "$?" "Docker run failed"
+  assert_equals "OK" "${RESULT}" "PHP run as www-data failed or printed errors"
+}
+
 setup_suite() {
   export TMP_DIR="$(mktemp -d)"
   if [[ $VARIANT == cli* ]]; then export CONTAINER_CWD=/usr/src/app; else export CONTAINER_CWD=/var/www/html; fi
diff --git a/utils/README.blueprint.md b/utils/README.blueprint.md
index bf7d61d..64c6971 100644
--- a/utils/README.blueprint.md
+++ b/utils/README.blueprint.md
@@ -353,6 +353,10 @@ working directory (`/var/www/html` for Apache/PHP-FPM, or `/usr/src/app` for CLI
 you want to run commands as this user. So it will **dynamically change the ID of the docker user** to match the ID of
 the current working directory user.
 
+If this ID is already used by a system account of the image (e.g. `998`, used by `systemd-network` in the image and
+often by the `gitlab-runner` user on CI hosts), this system account is moved to another ID: the commands are still run
+by the `docker` user.
+
 Furthermore, the image is changing the Apache default user/group to be `docker/docker` (instead if `www-data/www-data`).
 So Apache will run with the same rights as the user on your host.
 
diff --git a/utils/docker-entrypoint-as-root.sh b/utils/docker-entrypoint-as-root.sh
index d2e3b13..539ea9f 100755
--- a/utils/docker-entrypoint-as-root.sh
+++ b/utils/docker-entrypoint-as-root.sh
@@ -66,6 +66,24 @@ fi
 
 # DOCKER_USER is a user name if the user exists in the container, otherwise, it is a user ID (from a user on the host).
 
+# A system account of the image that has the ID of DOCKER_USER is moved to a free ID: the docker user takes this ID
+SYS_UID_MIN=$(awk '$1 == "SYS_UID_MIN" { print $2 }' /etc/login.defs)
+SYS_UID_MAX=$(awk '$1 == "SYS_UID_MAX" { print $2 }' /etc/login.defs)
+SYS_UID_MIN=${SYS_UID_MIN:-100}
+SYS_UID_MAX=${SYS_UID_MAX:-999}
+SYSTEM_ACCOUNT=$(getent passwd "$DOCKER_USER" | cut -d: -f1,3)
+SYSTEM_ACCOUNT_NAME=${SYSTEM_ACCOUNT%%:*}
+SYSTEM_ACCOUNT_ID=${SYSTEM_ACCOUNT##*:}
+if [[ -n "$SYSTEM_ACCOUNT" ]] && [[ "$SYSTEM_ACCOUNT_NAME" != "docker" ]] && (( SYSTEM_ACCOUNT_ID >= SYS_UID_MIN && SYSTEM_ACCOUNT_ID <= SYS_UID_MAX )); then
+    FREE_ID=$SYS_UID_MAX
+    while getent passwd "$FREE_ID" > /dev/null; do
+        FREE_ID=$((FREE_ID - 1))
+    done
+    sed -i "s/^${SYSTEM_ACCOUNT_NAME}:\([^:]*\):${SYSTEM_ACCOUNT_ID}:/${SYSTEM_ACCOUNT_NAME}:\1:${FREE_ID}:/" /etc/passwd
+    DOCKER_USER=$SYSTEM_ACCOUNT_ID
+fi
+unset SYS_UID_MIN SYS_UID_MAX SYSTEM_ACCOUNT SYSTEM_ACCOUNT_NAME SYSTEM_ACCOUNT_ID FREE_ID
+
 # If DOCKER_USER is an ID, let's
 if [[ "$DOCKER_USER" =~ ^[0-9]+$ ]] ; then
     # MAIN_DIR_USER is a user ID.
@@ -123,14 +141,14 @@ unset DOCKER_FOR_MAC_REMOTE_HOST
 unset REMOTE_HOST_FOUND
 
 sudo chown docker:docker /opt/php_env_var_cache.php
-/usr/bin/real_php /usr/local/bin/check_php_env_var_changes.php &> /dev/null
+/usr/bin/real_php -d display_errors=stderr /usr/local/bin/check_php_env_var_changes.php &> /dev/null
 
-/usr/bin/real_php /usr/local/bin/generate_conf.php > /etc/php/${PHP_VERSION}/mods-available/generated_conf.ini
-PHP_VERSION="${PHP_VERSION}" /usr/bin/real_php /usr/local/bin/setup_extensions.php | sudo bash
+/usr/bin/real_php -d display_errors=stderr /usr/local/bin/generate_conf.php > /etc/php/${PHP_VERSION}/mods-available/generated_conf.ini
+PHP_VERSION="${PHP_VERSION}" /usr/bin/real_php -d display_errors=stderr /usr/local/bin/setup_extensions.php | sudo bash
 
 # output on the logs can be done by writing on the "tini" PID. Useful for CRONTAB
 TINI_PID=`ps -e | grep tini | awk '{print $1;}'`
-/usr/bin/real_php /usr/local/bin/generate_cron.php $TINI_PID > /tmp/generated_crontab
+/usr/bin/real_php -d display_errors=stderr /usr/local/bin/generate_cron.php $TINI_PID > /tmp/generated_crontab
 chmod 0644 /tmp/generated_crontab
 
 # If generated_crontab is not empty, start supercronic
@@ -139,13 +157,13 @@ if [[ -s /tmp/generated_crontab ]]; then
 fi
 
 if [[ "$IMAGE_VARIANT" == "apache" ]]; then
-    /usr/bin/real_php /usr/local/bin/enable_apache_mods.php | bash
+    /usr/bin/real_php -d display_errors=stderr /usr/local/bin/enable_apache_mods.php | bash
 fi
 
 if [ -e /etc/container/startup.sh ]; then
     sudo -E -u "#$DOCKER_USER_ID" /etc/container/startup.sh
 fi
-sudo -E -u "#$DOCKER_USER_ID" sh -c "/usr/bin/real_php /usr/local/bin/startup_commands.php | bash"
+sudo -E -u "#$DOCKER_USER_ID" sh -c "/usr/bin/real_php -d display_errors=stderr /usr/local/bin/startup_commands.php | bash"
 
 if [[ "$APACHE_DOCUMENT_ROOT" == /* ]]; then
   export ABSOLUTE_APACHE_DOCUMENT_ROOT="$APACHE_DOCUMENT_ROOT"
diff --git a/utils/php_proxy.sh b/utils/php_proxy.sh
index d3dc5a0..f1ba90c 100755
--- a/utils/php_proxy.sh
+++ b/utils/php_proxy.sh
@@ -1,8 +1,11 @@
 #!/bin/bash
 
-sudo chown docker:docker /opt/php_env_var_cache.php
+# Users that cannot use sudo run PHP with the current configuration
+if ! sudo -n chown docker:docker /opt/php_env_var_cache.php 2> /dev/null; then
+  exec /usr/bin/real_php "$@"
+fi
 
-REGENERATE=$(/usr/bin/real_php /usr/local/bin/check_php_env_var_changes.php)
+REGENERATE=$(/usr/bin/real_php -d display_errors=stderr /usr/local/bin/check_php_env_var_changes.php)
 
 if [[ "$REGENERATE" != "0" ]] && [[ "$REGENERATE" != "1" ]]; then
   >&2 echo "Unexpected PHP proxy output:"
@@ -11,8 +14,8 @@ if [[ "$REGENERATE" != "0" ]] && [[ "$REGENERATE" != "1" ]]; then
 fi
 
 if [[ "$REGENERATE" == "1" ]]; then
-  /usr/bin/real_php /usr/local/bin/generate_conf.php | sudo tee "/etc/php/${PHP_VERSION}/mods-available/generated_conf.ini" > /dev/null
-  PHP_VERSION="${PHP_VERSION}" /usr/bin/real_php /usr/local/bin/setup_extensions.php | sudo bash
+  /usr/bin/real_php -d display_errors=stderr /usr/local/bin/generate_conf.php | sudo tee "/etc/php/${PHP_VERSION}/mods-available/generated_conf.ini" > /dev/null
+  PHP_VERSION="${PHP_VERSION}" /usr/bin/real_php -d display_errors=stderr /usr/local/bin/setup_extensions.php | sudo bash
 fi
 
 exec /usr/bin/real_php "$@"