Able to reproduce this issue on reported version 64.0.3282.140, on latest beta 65.0.3352.51, on latest canary 66.0.3344.0 using Mac 10.13.3, windows 10 and Ubuntu 14.04 with steps given in comment#0. i.e; The resource https://static.wixstatic.com/sites/3c31ea_946b918eba6967e48e3ab4ad3c372779_56.json.z?v=3 was preloaded using link preload but not used within a few seconds from the window's load event. Please make sure it Please make sure it has an appropriate `as` value and it is preloaded intentionally, error is seen in console.

Good Build: 61.0.3119.0
Bad Build: 61.0.3121.0

CHANGELOG URL:
 https://chromium.googlesource.com/chromium/src/+log/37003a1722d89acc689cd3911efceb583bad43e0..1f18863cc9b2a5fe463671f3eb60de2f95bbf283

Suspecting same form changelog.

@ yoav: Please confirm the bug and help in re-assigning if it is not related to your change.

Thanks!

Here are the preload instructions (you can also see them if you do a "view source"):

<link rel="preload" as="fetch" href="https://static.wixstatic.com/sites/3c31ea_711cb4047ffc570d46fe80080bd88bea_58.json.z?v=3"/>
<link rel="preload" as="fetch" href="https://static.wixstatic.com/sites/3c31ea_946b918eba6967e48e3ab4ad3c372779_56.json.z?v=3"/>

These resources are then loaded using XMLHttpRequest, and the prefetching is providing the expected benefit.

Also, the page also uses "preload" with as="script" and the works properly without any console warnings.

This is unrelated to above mentioned change and is not a regression.

Looking at the example page, I do see these resources being double downloaded and not being properly reused. Digging further, it seems like their credentials modes are off. XHR by default fetches resources with a "same-origin" credentials mode (unless the `withCredentials` attribute is set).

So when preloading such resources, you should set the `crossorigin` attribute on them, to make sure the preloaded request matches the "real" one's credentials mode.

So, WontFixing since WAI.