Silverstripe CMS needs to be installed on a web server. Content authors and website administrators use their web browser to access a web-based GUI to do their day-to-day work. Website designers and developers require access to the files on the server to update templates, website logic, and perform upgrades or maintenance.


  • PHP >=7.1
  • PHP extensions: ctype, dom, fileinfo, hash, intl, mbstring, session, simplexml, tokenizer, xml
  • PHP configuration: memory_limit with at least 48M
  • PHP extension for image manipulation: Either gd or imagick
  • PHP extension for a database connector (e.g. pdo or mysqli)

Use phpinfo() to inspect your configuration.


Connection mode (sql_mode) when using MySQL server >=5.7.5

In MySQL versions >=5.7.5, the ANSI sql_mode setting behaves differently and includes the ONLY_FULL_GROUP_BY setting. It is generally recommended to leave this setting as-is because it results in deterministic SQL. However, for some advanced cases, the sql_mode can be configured on the database connection via the configuration API (see MySQLDatabase::$sql_mode for more details.) This setting is only available in Silverstripe CMS 4.7 and later.

Webserver Configuration


SilverStripe needs to handle a variety of HTTP requests, and relies on the hosting environment to be configured securely to enforce restrictions. There are secure defaults in place for Apache, but you should be aware of the configuration regardless of your webserver setup.

Public webroot

The webroot of your webserver should be configured to the public/ subfolder. Projects created prior to SilverStripe 4.1 might be using the main project folder as the webroot. In this case, you are responsible for ensuring access to system files such as configuration in *.yml is protected from public access. We strongly recommend switching to more secure hosting via the public/. See 4.1.0 upgrading guide.

Filesystem permissions

SilverStripe needs write access for the webserver user to public/assets, and read access for that user on everything else in your webroot.


SilverStripe allows CMS authors to upload files into the public/assets/ folder, which should be served by your webserver. No PHP execution should be allowed in this folder. This is configured for Apache by default via public/assets/.htaccess. The file is generated dynamically during the dev/build stage.

Additionally, access is whitelisted by file extension through a dynamically generated whitelist based on the File.allowed_extensions setting (see File Security). This whitelist uses the same defaults configured through file upload through SilverStripe, so is considered a second line of defence.

Secure Assets

Files can be kept in draft stage, and access restricted to certain user groups. These files are stored in a special .protected folder (defaulting to public/assets/.protected). Requests to files in this folder should be denied by your webserver.

Requests to files in the .protected folder are routed to PHP by default when using Apache, through public/assets/.htaccess. If you are using another webserver, please follow our guides to ensure a secure setup. See Developer Guides: File Security for details.

Web Worker Concurrency

It's generally a good idea to run multiple workers to serve multiple HTTP requests to SilverStripe concurrently. The exact number depends on your website needs. The CMS attempts to request multiple views concurrently. It also routes protected and draft files through SilverStripe. This can increase your concurrency requirements, e.g. when authors batch upload and view dozens of draft files in the CMS.

When allowing upload of large files through the CMS (through PHP settings), these files might be used as protected and draft files. Files in this state get served by SilverStripe rather than your webserver. Since the framework uses PHP streams, this allows serving of files larger than your PHP memory limit. Please be aware that streaming operations don't count towards PHP's max_execution_time, which can risk exhaustion of web worker pools for long-running downloads.

URL Rewriting

SilverStripe expects URL paths to be rewritten to public/index.php. For Apache, this is preconfigured through .htaccess files, and expects using the mod_rewrite module. By default, these files are located in public/.htaccess and public/assets/.htaccess.

HTTP Headers

SilverStripe can add HTTP headers to reponses it handles directly. These headers are often sensitive, for example preventing HTTP caching for responses displaying data based on user sessions, or when serving protected assets. You need to ensure those headers are kept in place in your webserver. For example, Apache allows this through Header setifempty (see docs). See Developer Guide: Performance and Developer Guides: File Security for more details.

Silverstripe relies on the Host header to construct URLs such as "reset password" links, so you'll need to ensure that the systems hosting it only allow valid values for this header. See Developer Guide: Security - Request hostname forgery.

CDNs and other Reverse Proxies

If your Silverstripe site is hosted behind multiple HTTP layers, you're in charge of controlling which forwarded headers are considered valid, and which IPs can set them. See Developer Guide: Security - Request hostname forgery.


SilverStripe is a modular system, with modules installed and updated via the composer PHP dependency manager. These are usually stored in vendor/, outside of the public/ webroot. Since many modules rely on serving frontend assets such as CSS files or images, these are mapped over to the public/_resources/ folder automatically. If the filesystem supports it, this is achieved through symlinks. Depending on your hosting and deployment mechanisms, you may need to configure the plugin to copy files instead. See silverstripe/vendor-plugin for details.

Error pages

The default installation includes silverstripe/errorpage, which generates static error pages that bypass PHP execution when those pages are published in the CMS. Once published, the static files are located in public/assets/error-404.html and public/assets/error-500.html. The default public/.htaccess file is configured to have Apache serve those pages based on their HTTP status code.

Other webservers (Nginx, IIS, Lighttpd)

Serving through webservers other than Apache requires more manual configuration, since the defaults configured through .htaccess don't apply. Please apply the considerations above to your webserver to ensure a secure hosting environment. In particular, configure protected assets correctly to avoid exposing draft or protected files uploaded through the CMS.

There are various community supported installation instructions for different environments. Nginx is a popular choice, see Nginx webserver configuration.

SilverStripe is known to work with Microsoft IIS, and generates web.config files by default (see Microsoft IIS and SQL Server configuration).

Additionally, there are community supported guides for installing SilverStripe on various environments:

PHP Requirements for older SilverStripe releases

SilverStripe's PHP support has changed over time and if you are looking to upgrade PHP on your SilverStripe site, this table may be of use:

SilverStripe VersionPHP VersionMore information
3.0 - 3.55.3 - 5.6requirements docs
3.65.3 - 7.1
3.75.3 - 7.3changelog
4.0 - 4.45.6+
4.5+ (unreleased)7.1+blog post

CMS browser requirements

SilverStripe CMS supports the following web browsers:

  • Google Chrome
  • Internet Explorer 11
  • Microsoft Edge
  • Mozilla Firefox

We aim to provide satisfactory experiences in Apple Safari. SilverStripe CMS works well across Windows, Linux, and Mac operating systems.

End user requirements

SilverStripe CMS is designed to make excellent, standards-compliant websites that are compatible with a wide range of industry standard browsers and operating systems. A competent developer is able to produce websites that meet W3C guidelines for HTML, CSS, JavaScript, and accessibility, in addition to meeting specific guide lines, such as e-government requirements.