The resource was preloaded using link preload but not used within a few seconds

I’m using the W3 Total Cache plugin, and have set it to minify and combine CSS and JS files.

I have also set it to use the HTTP2 preloading capabilities, though, when I load the site in Chrome, I’m seeing the following error in the console for both the CSS and JS files:

The resource [RESOURCE URL HERE] was preloaded using link preload but not used within a few seconds from the window's load event. Please make sure it wasn't preloaded for nothing.

Why is that showing up? The script and the stylesheet are indeed being used, they are clearly declared in the usual places.

I looked in the Network tab of the console, and the script and the stylesheet are both in the ‘memory cache’ initially, and are then downloaded a second time!

What could I be doing wrong?

Just try to disable “HTTP/2 push” under the Minify section of W3 Total Cache.

Most probably your apache server (or whatever web server you are using) does not support http2. The browser understands that, and it’s trying to tell you that the preload is not worth it.

More about the difference between http1.1 and http2, you can find here.