diff --git a/start.sh b/start.sh
index ac9db80470ea1e9c373cf6e8c1b82c3f6e1283a4..7ff7e09b9e67d06845954cd42128aad86e95e15d 100755
--- a/start.sh
+++ b/start.sh
@@ -13,53 +13,49 @@ TARGET_DIR=/var/www/webmail
 # Name of the MySQL database to use.
 MYSQL_DB="ai_roundcube"
 
-install_config() {
-    install -o root -g root -m 644 ${CONFIG_DIR}/config.inc.php ${TARGET_DIR}/config/config.inc.php
-
-    # For each known plugin, look for a NAME.config.inc.php file in
-    # the config directory: if found, copy it to the plugin directory
-    # as plugins/NAME/config.inc.php.
-    for p in $(cd ${TARGET_DIR}/plugins && echo *) ; do
-        if [ -e "${CONFIG_DIR}/${p}.config.inc.php" ]; then
-            install -o root -g root -m 644 ${CONFIG_DIR}/${p}.config.inc.php \
-                    ${TARGET_DIR}/plugins/${p}/config.inc.php
-        fi
-    done
-}
-
-setup_database() {
-    # The current Roundcube version is stored in the database.
-    cur_version=$(mysql -NBe 'select version from rc_version' ${MYSQL_DB} 2>/dev/null)
-
-    # If cur_version is empty, it means that the database has not been
-    # initialized yet.
-    if [ -z "${cur_version}" ]; then
-        mysql ${MYSQL_DB} < ${TARGET_DIR}/SQL/mysql.initial.sql
-        mysql -e "create table rc_version (version text); insert into rc_version (version) values ('unknown')" ${MYSQL_DB}
-    fi
-    
-    # Run database upgrade if necessary.
-    ${TARGET_DIR}/bin/update.sh -v ${cur_version} -y
-
-    mysql -e "update rc_version set version='${RC_VERSION}'" ${MYSQL_DB}
+die() {
+    echo "ERROR: $*" >&2
+    exit 1
 }
 
-
-set -e
-set -u
-
 # Abort if some fundamental environment variables are not defined.
-# This is nicer than having Apache die with an error.
-if [ -z "${DOMAIN}" ]; then
-    echo "ERROR: The 'DOMAIN' environment variable is not defined" >&2
-    exit 1
-fi
-if [ -z "${SHARD_ID}" ]; then
-    echo "ERROR: The 'SHARD_ID' environment variable is not defined" >&2
-    exit 1
+# This is nicer than having Apache die with an error later.
+test -n "${DOMAIN}" \
+    || die "the 'DOMAIN' environment variable is not defined"
+test -n "${SHARD_ID}" \
+    || die "the 'SHARD_ID' environment variable is not defined"
+
+# Install the main Roundcube configuration to TARGET_DIR/config.
+test -e ${CONFIG_DIR}/config.inc.php \
+    || die "${CONFIG_DIR}/config.inc.php is missing"
+install -o root -g root -m 644 ${CONFIG_DIR}/config.inc.php ${TARGET_DIR}/config/config.inc.php
+
+# For each known plugin, look for a NAME.config.inc.php file in
+# the config directory: if found, copy it to the plugin directory
+# as plugins/NAME/config.inc.php.
+for p in $(cd ${TARGET_DIR}/plugins && echo *) ; do
+    test -e "${CONFIG_DIR}/${p}.config.inc.php" \
+        && install -o root -g root -m 644 ${CONFIG_DIR}/${p}.config.inc.php \
+                   ${TARGET_DIR}/plugins/${p}/config.inc.php
+done
+
+# Now set up the MySQL database for Roundcube. The current Roundcube
+# version is stored in the database.
+cur_version=$(mysql -NBe 'select version from rc_version' ${MYSQL_DB} 2>/dev/null)
+
+# If cur_version is empty, it means that the database has not been
+# initialized yet.
+if [ -z "${cur_version}" ]; then
+    mysql ${MYSQL_DB} < ${TARGET_DIR}/SQL/mysql.initial.sql \
+        || die "could not load initial SQL schema to ${MYSQL_DB}"
+    mysql -e "create table rc_version (version text); insert into rc_version (version) values ('unknown')" ${MYSQL_DB} \
+        || die "could not create rc_version table in ${MYSQL_DB}"
 fi
+    
+# Run database upgrade if necessary.
+${TARGET_DIR}/bin/update.sh -v ${cur_version} -y \
+    || die "Roundcube update script failed"
 
-install_config
-setup_database
+mysql -e "update rc_version set version='${RC_VERSION}'" ${MYSQL_DB}
 
 exit 0