Responses that contain a NUL byte in their headers result in an "failed to load resource: Response contained invalid HTTP headers" and do not generate a PerformanceResourceTiming object entry. The specifications state that > If a resource fetch was aborted due to a networking error (e.g. DNS, TCP, or TLS error), then the fetch will be included as a PerformanceResourceTiming object in the Performance Timeline with only the startTime, fetchStart, duration and responseEnd set. https://w3c.github.io/resource-timing/#resources-included-in-the-performanceresourcetiming-interface Thus, I believe an entry should be created here. Example URL: http://sub.headers.websec.saarland/_hp/tests/perfAPI-tao.sub.html?resp_type=parsing&browser_id=1&label=TAO&first_id=42874&last_id=42883&scheme=http&t_resp_id=42875&t_element_relation=img_direct&t_resp_origin=https://headers.webappsec.eu In Firefox and Chromium an entry is created.
<rdar://problem/126912722>