WordPress 5.5 will be released on August 11, 2020 with a new feature. With new version 5.5 – WordPress will expose a sitemap index at:

/wp-sitemap.xml

This is the main XML file that contains the listing of all the sitemap pages exposed by a WordPress site. The sitemap index can hold a maximum of 50000 sitemaps, and a single sitemap can hold a (filterable) maximum of 2000 entries.

By default, sitemaps are created for all public and publicly queryable post types and taxonomies, as well as for author archives and of course the homepage of the site. The robots.txt file exposed by WordPress will reference the sitemap index so that it can be easily discovered by search engines.

Technical Requirements: Rendering sitemaps on the front-end requires the SimpleXML PHP extension. If this extension is not available, an error message will be displayed instead of the sitemap. The HTTP status code 501 (“Not implemented”) will be sent accordingly.

Technical Requirements missing in Synology NAS DSM: If you host your website from home using a Synology NAS you will notice that the SimpleXML PHP extension is not present in Web Station PHP Settings / General Settings / PHP Extension area. This is a big problem and I hope Synology can fix it soon, very soon. So, today we are missing two important PHP extensions in our Synology NAS DSM that can compromise the basic functionality of WordPress. The first missing PHP extension is Imagick while the second missing PHP extension is SimpleXML. The lack of these two PHP extensions compromises the optimal functionality of WordPress itself.
UPDATE 10.8.2020 SimpleXML is a Core module and therefore always activated on Synology NAS.

Do Hosting Providers Support SimpleXML? WordPress solicited feedback from the hosting community regarding the SimpleXML PHP extension to see if this was already integrated. Failure to integrate this PHP extension would cause the WordPress sitemap functionality to fail. GoDaddy, IONOS (formerly 1and1) and other hosts responded that this was already implemented into their servers, including in shared host environments.

All web hosts will be required to install a new extension called SimpleXML PHP. WordPress’s sitemaps will require this extension to work and they will not function if it is not installed, so this will become mandatory for every hosting provider.

UPDATE 15.9.2020

Note: New PHP 7.4 support imagick extension. It has been nearly a year since hundreds of users asked Synology to implement the Imagick extension in PHP. Up until now there is no response and no implementation has been carried out. My biggest fear is that the SimpleXML PHP extension won’t even be implemented. Ever. So, I am asking @Synology with this public post to add the Imagick PHP extension and the SimpleXML PHP extension. Implementing these two extensions won’t take long, maybe 30 minutes tops. Synology, please don’t forget us, your Synology NAS users relying on you for web hosting!

UPDATE 10.8.2020

Today I have received very good news from Synology!

Dear Mr Lixandru,

Thank you for contacting Synology Technical Support.

SimpleXML is a Core module and therefore always activated.

Here is the output for php -m:

root@username_NAS:~# php -m
[PHP Modules]
bcmath
bz2
Core
ctype
curl
date
dom
ereg
filter
hash
iconv
json
ldap
libxml
mbstring
mcrypt
openssl
pcntl
pcre
PDO
pdo_sqlite
Phar
posix
readline
Reflection
session
shmop
SimpleXML
sockets
SPL
sqlite3
standard
syno_compiler
xml
xmlreader
xmlwriter
zip
zlib

[Zend Modules]

Note: I can confirm the SimpleXML extension is working correctly with WordPress 5.5 installed on my Synology NAS and the wp-sitemap.xml page is rendering perfectly, without any issues!

This post was updated on Tuesday / September 15th, 2020 at 5:06 PM