diff --git a/docker-entrypoint.sh b/docker-entrypoint.sh
index b6da893b..413ae9c6 100755
--- a/docker-entrypoint.sh
+++ b/docker-entrypoint.sh
@@ -101,92 +101,114 @@ if expr "$1" : "apache" 1>/dev/null || [ "$1" = "php-fpm" ] || [ "${NEXTCLOUD_UP
         else
             rsync_options="-rlD"
         fi
-        rsync $rsync_options --delete --exclude-from=/upgrade.exclude /usr/src/nextcloud/ /var/www/html/
 
-        for dir in config data custom_apps themes; do
-            if [ ! -d "/var/www/html/$dir" ] || directory_empty "/var/www/html/$dir"; then
-                rsync $rsync_options --include "/$dir/" --exclude '/*' /usr/src/nextcloud/ /var/www/html/
-            fi
-        done
-        rsync $rsync_options --include '/version.php' --exclude '/*' /usr/src/nextcloud/ /var/www/html/
-        echo "Initializing finished"
+        # If another process is syncing the html folder, wait for
+        # it to be done, then escape initalization
+        lock=/var/www/html/nextcloud-init-sync.lock
+        count=0
 
-        #install
-        if [ "$installed_version" = "0.0.0.0" ]; then
-            echo "New nextcloud instance"
-
-            file_env NEXTCLOUD_ADMIN_PASSWORD
-            file_env NEXTCLOUD_ADMIN_USER
-
-            if [ -n "${NEXTCLOUD_ADMIN_USER+x}" ] && [ -n "${NEXTCLOUD_ADMIN_PASSWORD+x}" ]; then
-                # shellcheck disable=SC2016
-                install_options='-n --admin-user "$NEXTCLOUD_ADMIN_USER" --admin-pass "$NEXTCLOUD_ADMIN_PASSWORD"'
-                if [ -n "${NEXTCLOUD_DATA_DIR+x}" ]; then
-                    # shellcheck disable=SC2016
-                    install_options=$install_options' --data-dir "$NEXTCLOUD_DATA_DIR"'
-                fi
-
-                file_env MYSQL_DATABASE
-                file_env MYSQL_PASSWORD
-                file_env MYSQL_USER
-                file_env POSTGRES_DB
-                file_env POSTGRES_PASSWORD
-                file_env POSTGRES_USER
-
-                install=false
-                if [ -n "${SQLITE_DATABASE+x}" ]; then
-                    echo "Installing with SQLite database"
-                    # shellcheck disable=SC2016
-                    install_options=$install_options' --database-name "$SQLITE_DATABASE"'
-                    install=true
-                elif [ -n "${MYSQL_DATABASE+x}" ] && [ -n "${MYSQL_USER+x}" ] && [ -n "${MYSQL_PASSWORD+x}" ] && [ -n "${MYSQL_HOST+x}" ]; then
-                    echo "Installing with MySQL database"
-                    # shellcheck disable=SC2016
-                    install_options=$install_options' --database mysql --database-name "$MYSQL_DATABASE" --database-user "$MYSQL_USER" --database-pass "$MYSQL_PASSWORD" --database-host "$MYSQL_HOST"'
-                    install=true
-                elif [ -n "${POSTGRES_DB+x}" ] && [ -n "${POSTGRES_USER+x}" ] && [ -n "${POSTGRES_PASSWORD+x}" ] && [ -n "${POSTGRES_HOST+x}" ]; then
-                    echo "Installing with PostgreSQL database"
-                    # shellcheck disable=SC2016
-                    install_options=$install_options' --database pgsql --database-name "$POSTGRES_DB" --database-user "$POSTGRES_USER" --database-pass "$POSTGRES_PASSWORD" --database-host "$POSTGRES_HOST"'
-                    install=true
-                fi
-
-                if [ "$install" = true ]; then
-                    echo "starting nextcloud installation"
-                    max_retries=10
-                    try=0
-                    until run_as "php /var/www/html/occ maintenance:install $install_options" || [ "$try" -gt "$max_retries" ]
-                    do
-                        echo "retrying install..."
-                        try=$((try+1))
-                        sleep 10s
-                    done
-                    if [ "$try" -gt "$max_retries" ]; then
-                        echo "installing of nextcloud failed!"
-                        exit 1
-                    fi
-                    if [ -n "${NEXTCLOUD_TRUSTED_DOMAINS+x}" ]; then
-                        echo "setting trusted domains…"
-                        NC_TRUSTED_DOMAIN_IDX=1
-                        for DOMAIN in $NEXTCLOUD_TRUSTED_DOMAINS ; do
-                            DOMAIN=$(echo "$DOMAIN" | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//')
-                            run_as "php /var/www/html/occ config:system:set trusted_domains $NC_TRUSTED_DOMAIN_IDX --value=$DOMAIN"
-                            NC_TRUSTED_DOMAIN_IDX=$(($NC_TRUSTED_DOMAIN_IDX+1))
-                        done
-                    fi
-                else
-                    echo "running web-based installer on first connect!"
-                fi
-            fi
-        #upgrade
+        if [ -f "$lock" ]; then
+            until [ ! -f "$lock" ]
+            do
+                count=$((count+1))
+                wait=$((count*10))
+                echo "Another process is initializing Nextcloud. Waiting $wait seconds..."
+                sleep $wait
+            done
+            echo "The other process is done, assuming complete initialization"
         else
-            run_as 'php /var/www/html/occ upgrade'
+            # Prevent multiple images syncing simultaneously
+            touch $lock
+            rsync $rsync_options --delete --exclude-from=/upgrade.exclude /usr/src/nextcloud/ /var/www/html/
 
-            run_as 'php /var/www/html/occ app:list' | sed -n "/Enabled:/,/Disabled:/p" > /tmp/list_after
-            echo "The following apps have been disabled:"
-            diff /tmp/list_before /tmp/list_after | grep '<' | cut -d- -f2 | cut -d: -f1
-            rm -f /tmp/list_before /tmp/list_after
+            for dir in config data custom_apps themes; do
+                if [ ! -d "/var/www/html/$dir" ] || directory_empty "/var/www/html/$dir"; then
+                    rsync $rsync_options --include "/$dir/" --exclude '/*' /usr/src/nextcloud/ /var/www/html/
+                fi
+            done
+            rsync $rsync_options --include '/version.php' --exclude '/*' /usr/src/nextcloud/ /var/www/html/
 
+            # Install
+            if [ "$installed_version" = "0.0.0.0" ]; then
+                echo "New nextcloud instance"
+
+                file_env NEXTCLOUD_ADMIN_PASSWORD
+                file_env NEXTCLOUD_ADMIN_USER
+
+                if [ -n "${NEXTCLOUD_ADMIN_USER+x}" ] && [ -n "${NEXTCLOUD_ADMIN_PASSWORD+x}" ]; then
+                    # shellcheck disable=SC2016
+                    install_options='-n --admin-user "$NEXTCLOUD_ADMIN_USER" --admin-pass "$NEXTCLOUD_ADMIN_PASSWORD"'
+                    if [ -n "${NEXTCLOUD_DATA_DIR+x}" ]; then
+                        # shellcheck disable=SC2016
+                        install_options=$install_options' --data-dir "$NEXTCLOUD_DATA_DIR"'
+                    fi
+
+                    file_env MYSQL_DATABASE
+                    file_env MYSQL_PASSWORD
+                    file_env MYSQL_USER
+                    file_env POSTGRES_DB
+                    file_env POSTGRES_PASSWORD
+                    file_env POSTGRES_USER
+
+                    install=false
+                    if [ -n "${SQLITE_DATABASE+x}" ]; then
+                        echo "Installing with SQLite database"
+                        # shellcheck disable=SC2016
+                        install_options=$install_options' --database-name "$SQLITE_DATABASE"'
+                        install=true
+                    elif [ -n "${MYSQL_DATABASE+x}" ] && [ -n "${MYSQL_USER+x}" ] && [ -n "${MYSQL_PASSWORD+x}" ] && [ -n "${MYSQL_HOST+x}" ]; then
+                        echo "Installing with MySQL database"
+                        # shellcheck disable=SC2016
+                        install_options=$install_options' --database mysql --database-name "$MYSQL_DATABASE" --database-user "$MYSQL_USER" --database-pass "$MYSQL_PASSWORD" --database-host "$MYSQL_HOST"'
+                        install=true
+                    elif [ -n "${POSTGRES_DB+x}" ] && [ -n "${POSTGRES_USER+x}" ] && [ -n "${POSTGRES_PASSWORD+x}" ] && [ -n "${POSTGRES_HOST+x}" ]; then
+                        echo "Installing with PostgreSQL database"
+                        # shellcheck disable=SC2016
+                        install_options=$install_options' --database pgsql --database-name "$POSTGRES_DB" --database-user "$POSTGRES_USER" --database-pass "$POSTGRES_PASSWORD" --database-host "$POSTGRES_HOST"'
+                        install=true
+                    fi
+
+                    if [ "$install" = true ]; then
+                        echo "Starting nextcloud installation"
+                        max_retries=10
+                        try=0
+                        until run_as "php /var/www/html/occ maintenance:install $install_options" || [ "$try" -gt "$max_retries" ]
+                        do
+                            echo "Retrying install..."
+                            try=$((try+1))
+                            sleep 10s
+                        done
+                        if [ "$try" -gt "$max_retries" ]; then
+                            echo "Installing of nextcloud failed!"
+                            exit 1
+                        fi
+                        if [ -n "${NEXTCLOUD_TRUSTED_DOMAINS+x}" ]; then
+                            echo "Setting trusted domains…"
+                            NC_TRUSTED_DOMAIN_IDX=1
+                            for DOMAIN in $NEXTCLOUD_TRUSTED_DOMAINS ; do
+                                DOMAIN=$(echo "$DOMAIN" | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//')
+                                run_as "php /var/www/html/occ config:system:set trusted_domains $NC_TRUSTED_DOMAIN_IDX --value=$DOMAIN"
+                                NC_TRUSTED_DOMAIN_IDX=$(($NC_TRUSTED_DOMAIN_IDX+1))
+                            done
+                        fi
+                    else
+                        echo "Please run the web-based installer on first connect!"
+                    fi
+                fi
+            # Upgrade
+            else
+                run_as 'php /var/www/html/occ upgrade'
+
+                run_as 'php /var/www/html/occ app:list' | sed -n "/Enabled:/,/Disabled:/p" > /tmp/list_after
+                echo "The following apps have been disabled:"
+                diff /tmp/list_before /tmp/list_after | grep '<' | cut -d- -f2 | cut -d: -f1
+                rm -f /tmp/list_before /tmp/list_after
+
+            fi
+
+            # Initialization done, reset lock
+            rm $lock
+            echo "Initializing finished"
         fi
     fi
 fi
diff --git a/upgrade.exclude b/upgrade.exclude
index 354864da..31ce39a8 100644
--- a/upgrade.exclude
+++ b/upgrade.exclude
@@ -3,3 +3,4 @@
 /custom_apps/
 /themes/
 /version.php
+/nextcloud-init-sync.lock