Hi, I’m testing file uploads to a web app that sits behind an AWS Application Load Balancer, and I need a way to make Safari use HTTP/1.1 instead of HTTP/2 while I test. What I’m seeing: Uploads up to about 4 MB work. Anything bigger slows down more and more and then fails with a network error. A 49 MB file never finishes. The same upload over HTTP/1.1 works every time. I tested this with curl (--http1.1 against --http2), and with Chrome started with --disable-http2. In that Chrome, the 49 MB file uploaded fine. In Safari, which uses HTTP/2 with this server, the same file fails every time. My questions: Is there any way to make Safari use HTTP/1.1 for a site, or turn HTTP/2 off, for testing? For example a hidden setting, a defaults write key, something under Develop → Feature Flags, or a Web Inspector option. I couldn’t find one. If not, is there a recommended way to test how Safari behaves with HTTP/1.1 only? Safari supports HTTP/3. Our load balancer doesn’t offer HTTP/3 at the moment, but if it did, would Safari switch to it automatically for uploads? And are large uploads over HTTP/3 known to behave better than over HTTP/2? I have also asked AWS about the load balancer side. The long-term plan is to switch HTTP/2 off there, but I’d like to be able to confirm the behaviour in Safari directly in the meantime. Thank you