Enable HTTP/2 support in Plesk: Instructions, benefits and best practices

The activation of HTTP/2 Plesk brings faster loading times, more efficient data transfer and better security for SSL-secured websites. In this guide, I will show you step by step how to activate HTTP/2 in Plesk, what advantages you can expect and how to fix possible errors.

Key points

• Activate HTTP/2: One command is sufficient for global activation in Plesk
• Better performance: Faster loading times through multiplexing and compression
• Plesk requirementsVersion 12.5.30 or higher required, as well as Nginx and SSL
• Optimization options: Use additional features such as GZip after activation
• Important for SEOHTTP/2 improves PageSpeed and is preferred by search engines

What is HTTP/2 - and what are its technical benefits?

HTTP/2 is the revised version of the HTTP/1.1 protocol, which was the web standard for a long time. With HTTP/2, the Data transmission of modern websites. Technologies such as multiplexing allow several requests to be processed simultaneously via a TCP connection. In addition, compression and the server-side push function ensure that content is delivered in a targeted and timely manner. HTTP/2 always works via encrypted HTTPS connections (TLS) - a major advantage compared to older protocols. This combination of higher speed and security makes HTTP/2 almost indispensable for operators of current websites. In addition, so-called headers are compressed, which reduces the amount of data and further speeds up server-client communication. These advantages add up noticeably, especially for complex websites with many integrated scripts and files. Many administrators used to ask themselves whether they could simply continue to use HTTP/1.1. Although HTTP/1.1 is still active in many environments, performance will deteriorate in the long term if more and more users access high-quality content (images, videos, large libraries) at the same time. With HTTP/2, so-called "head-of-line blocking" is much less possible, which processes simultaneous requests faster and therefore allows better utilization of modern web technologies.

Requirements for HTTP/2 activation in Plesk

Before you activate HTTP/2 on your Plesk server, you must check a few points. HTTP/2 cannot be implemented correctly without these prerequisites. These requirements must be met:

• Plesk versionHTTP/2 is supported as of version 12.5.30
• Nginx web serverMust be installed and set up as a reverse proxy
• SSL CertificateYour domain must be encrypted and accessible via HTTPS

If one of these elements is missing, HTTP/2 will not work - even if it is activated. A free SSL certificate can be set up via the Plesk interface with just a few clicks. In this context, I recommend the instructions Create Let's Encrypt certificate in Plesk. Also note that when setting up Nginx as a reverse proxy, make sure that Apache (if available) is also configured correctly. Although Plesk relies on Nginx and Apache in tandem by default, communication should be clearly regulated. If the ports or redirects are set up incorrectly, this could lead to unexpected errors that only become noticeable after a while.

Activating HTTP/2 in Plesk - how it works

As soon as the technical requirements are met, you can activate HTTP/2 with a single command. To do this, log in to your server as root via SSH and execute the following command:

plesk bin http2_pref enable

This enables HTTP/2 server-wide for all SSL-enabled domains. The existing Nginx configuration is automatically extended so that you do not have to make any adjustments to configuration files. If HTTP/2 is active, Nginx takes over the optimized transfer of all data. If you want to check the status, you can use your browser's developer tools or external tools such as the KeyCDN HTTP/2 test. In the browser developer tools (e.g. in Chrome or Firefox), you will find information on whether a connection was established via h2 (HTTP/2) or http/1.1 under the network tab. Pay attention to possible misconfigurations due to browser caches by regularly clearing the cache and reloading the page.

Can I activate HTTP/2 only for certain domains?

In Plesk, the HTTP/2 setting applies globally - for all domains with HTTPS on a server. This means that it is currently not possible to selectively activate or deactivate HTTP/2 for individual projects. If you still want to deactivate HTTP/2, use the following command:

plesk bin http2_pref disable

This can be useful, for example, if you are testing specific web applications that do not (yet) fully support HTTP/2. Single-domain management of the HTTP/2 function is currently not provided.

Optimizations after HTTP/2 activation

After successfully activating HTTP/2 in Plesk, you can take further measures to utilize its full potential. HTTP/2 only really shows its efficiency when the content delivered to the server is optimized accordingly. You should check these points: - Activate GZip compression on the Nginx server - Combine CSS and JavaScript files to better utilize HTTP/2 multiplexing - Reduce HTML headers and cookie sizes to further reduce transfer times Efficient resource handling in particular makes it possible to handle large numbers of visitors while maintaining stable performance. You can also use so-called Server push-HTTP/2 functionalities to deliver critical resources (such as important CSS files) directly with the request, without having to wait for the client's second request. This reduces latency and helps users to load pages more quickly.

Table: Advantages of HTTP/2 at a glance

The following table shows you the most important properties of HTTP/2 compared to HTTP/1.1:

Technology	HTTP/1.1	HTTP/2
Connections	Individually & one after the other	Parallel (multiplexing)
Header size	Larger & uncompressed	Efficiently compressed
Encryption	Optional	Mandatory
Server Push	No	Yes
PageSpeed/SEO	Moderate	Significantly better

HTTP/2 and WordPress - an ideal combination

WordPress pages benefit greatly from HTTP/2, as many simultaneous resources (JS, CSS, fonts) have to be loaded. With HTTP/2 activated, the Loading time and caching also works more efficiently. You can use the Plesk panel together with the "Security Advisor" extension to activate HTTP/2 and HTTPS for WordPress websites - directly from the user interface. If you have just set up WordPress, take a look at the Step-by-step installation in Pleskso that no important setting is overlooked. Themes that integrate many scripts in particular benefit from parallel delivery, as the waiting time for the user is greatly reduced each time the page is called up. WordPress also provides regular updates, some of which also take performance aspects into account. HTTP/2 also provides a modern basis for serving visitors quickly and securely.

Typical sources of error and possible solutions

Problems rarely occur after activating HTTP/2 - for example, if outdated software components are involved. Sources of errors are often a lack of ALPN support or an incompatible SSL configuration. In such cases, check the Nginx log files for indications. If necessary, use the deactivation command to perform a rollback. The following Linux distributions are supported: - CentOS 7 - RHEL 7 - Ubuntu 14.04/16.04 - Debian 8 It is just as important to check JPEG compression and image optimization, as large-format images often slow down the speed of a website. You should already pay attention to efficient formats (e.g. WebP) when uploading to the media library or embedding in WordPress. Sometimes a rewrite error can also be a hurdle - especially if you have stored individual rules in .htaccess files. Make sure that your redirects do not redirect to unencrypted connections.

Best practices for productive operation

If your server is running with HTTP/2, you should ensure this status on an ongoing basis. You can do this with regular checks and useful tools. For example, use the built-in Security Advisor in Plesk for automatic encryption, port checks or performance checks. I also recommend removing HTTP/1.1 elements that are no longer used. These include old redirects or uncompressed resources. Deactivate unused services such as FTP or POP3 to save resources - you can find out more about this in this Firewall configuration guide for Plesk. The combination with caching mechanisms has also proven itself for smooth operation. Varnish or Redis can be integrated for this purpose, provided your hosting tariff or server configuration allows this. To prevent bottlenecks, you should regularly analyze the log files of your web server. If there are a lot of timeout errors or unusual peaks in the access load, this may indicate configuration errors. With monitoring tools, it is possible to keep an eye on CPU utilization, RAM consumption and I/O performance, among other things. Also take the time to keep TLS certificates up to date. If a certificate expires, you will not be able to use HTTP/2, even if it is enabled on the server side. As Plesk offers integrated Let's Encrypt functions, the certificates can be easily renewed. However, should a certificate problem occur, it is recommended that you first create a new Let's Encrypt certificate and configure it for the affected domain.

Further tips for working with HTTP/2

Once you have activated HTTP/2, it is worth examining your own project for possible front-end optimizations. Because even with HTTP/2, poor code structures or untargeted loading of scripts can reduce performance. A central approach is the Lazy Loading of images, which means that when the page is called up, only the visible area graphics are initially loaded. Only when the user scrolls further are the remaining images loaded. This reduces the initial amount of data and thus speeds up the visible page layout. Bundling icons using SVG sprites or using icon fonts to accommodate several icons in one file is just as useful. This allows you to benefit from multiplexing, as fewer connections need to be established at the same time. Minification is recommended for JavaScript and CSS files - i.e. compressing them and removing comments, spaces or unnecessary characters. Especially with numerous plugins in content management systems such as WordPress, it can happen that many small JS/CSS files accumulate. A plugin that automatically minimizes and combines these files can help. Another technical tip: The "HTTP/2 Server Push" feature allows content to be sent to the client earlier, before the browser requests it. Although this feature is not always fully utilized by all browsers and you should follow the browser manufacturer's updates, it can bring loading time advantages in certain scenarios. For example, you can push the most important CSS files and make them available to the client before the first rendering. However, this requires a specific server configuration and is not active by default in every hosting package. Therefore, ask your provider whether you can make the appropriate settings in Plesk yourself or whether special configurations are required. If you manage many different domains or subdomains, you can keep an overview in Plesk by using the server health dashboard. There you can see at a glance how busy your server is and whether your websites are running smoothly. It is also a useful routine to receive regular reports in which you can track the load and possible outages. User numbers and PageSpeed changes are often directly recognizable so that you can initiate improvements at an early stage. In terms of SEO, you should track how search engines such as Google and Bing react to your pages. Faster loading times, especially on mobile devices, often have a positive effect on the ranking. Thanks to HTTP/2, not only the time-to-first-byte (TTFB) is shortened, but usually also the entire page structure. This improves the user experience and sends valuable signals to Google's search algorithm. So you kill two birds with one stone: your website becomes more secure and your ranking in the search results can also benefit.

Comparison: Hosting providers with HTTP/2 and Plesk

The choice of hosting provider influences the performance of your website. The following overview shows providers that combine HTTP/2 and Plesk:

Place	Provider	HTTP/2 support	Plesk support	Special features
1	Webhoster.com	Yes	Yes	High performance, excellent support
2	Provider B	Yes	Yes	Extensive portfolio
3	Provider C	Yes	Yes	Beginner-friendly

To summarize: HTTP/2 pays off

With HTTP/2 enabled in Plesk, you can get the most out of your website - both in terms of speed and security. The changeover is simple, fast and stable. In combination with HTTPS, a modern hosting environment and Nginx as a reverse proxy, you can achieve a high-performance and future-proof server configuration. Maintain your server regularly, test new features and keep your setup up to date - so your projects remain professional and competitive.