Use HTTP/2 for all of its resources

This means that the URL in question does not use HTTP/2 for all first-party page resources.

Why is this important?

The HTTP/1.1 standard was officially released in 1997, and much has changed since then. HTTP/2 came out in 2015, and offers many benefits over HTTP/1.1, including binary headers, multiplexing and server push. However, it is only recently that HTTP/2 has gained widespread browser support, which has limited its impact.

Now, however, it has become a de facto performance recommendation. Simply put, HTTP/2 serves your page's resources faster and with less data moving over the wire.

What does the Hint check?

This Hint will trigger for any internal URL that contains first-party resources that are not served over HTTP/2.

How do you resolve this issue?

Upgrading to HTTP/2 requires server work, so this sort of work will typically need a developer to get involved. You may also need to contact your web hosting provider to ensure that;

1. Your web server is able to support HTTP/2
2. Your server is configured to use HTTP/2

Depending on your server and configuration, this may require additional work.

Further Reading

• Does not use HTTP/2 for all of its resources (Lighthouse documentation)
• Introduction to HTTP/2 - Google Web Fundamentals
• Intro Guide to HTTP/2 for SEOs