Related but not duplicate: Chrome cancels URL_REQUEST after exactly 3 seconds
=> this question has been wrongly marked as Resolved. Here, I try to bring new elements to understand what is going on.

TLDR and questions:

Chromium-based browsers are canceling requests taking more than 3 seconds if the URL was written without http(s):// then making another request, resulting in 2 hits server-side. (see detailed logs below)

• a) Is there a way to modify this behavior?
  In other words, a way to tell Chromium browsers to “wait more” instead of canceling the request and doing another one.

• b) How do you handle it? Or maybe a way to avoid it, other than improving performances of the URL, of course 🙂

Findings and summary:

• this issue seems to occur only in Chromium-based browsers (Google Chrome, Microsoft Edge, …)
• this issue seems to occur only if you try to access any URL without specifying the scheme http:// or https.
• this issue occurs whether the domain has a http->https redirect or not. (see detailed logs below)
• this issue has nothing to do with HSTS. I’ve tested it: with HSTS enabled, Chrome just replaces the 301/302 http->https redirect to a 307 internal redirect request instead)
• this issue appears both with HTTP/1 and HTTP2 (tested in 2 different servers)
• this issue appears only when the initial request is taking at least 3 seconds.

Detailed logs:

1. Without HTTP => HTTPS redirection in the global vhost configuration

# Apache logs
[24/May/2024:15:35:54] 1.2.3.4 - www.example.com:443 "GET /testing HTTP/1.1" 200 "www.example.com/testing" bytes:34 time:4042159
[24/May/2024:15:35:57] 1.2.3.4 - www.example.com:80  "GET /testing HTTP/1.1" 200 "www.example.com/testing" bytes:34 time:4027890
[24/May/2024:15:36:01] 1.2.3.4 - www.example.com:80  "GET /favicon.ico HTTP/1.1" 200 "www.example.com/favicon.ico" bytes:0 time:326

# PHP logs
[2024-05-24 15:35:54.478306] 1.2.3.4 local.INFO: [REQUESTED_AT_15:35:54.477500] [https://www.example.com/testing] Request received, now I will wait 4 s
[2024-05-24 15:35:57.290657] 1.2.3.4 local.INFO: [REQUESTED_AT_15:35:57.290000] [http://www.example.com/testing]  Request received, now I will wait 4 s
[2024-05-24 15:35:58.478763] 1.2.3.4 local.INFO: [REQUESTED_AT_15:35:54.477500] [https://www.example.com/testing] Done, I waited 4 s! It is now 15:35:58.478700
[2024-05-24 15:36:01.291083] 1.2.3.4 local.INFO: [REQUESTED_AT_15:35:57.290000] [http://www.example.com/testing]  Done, I waited 4 s! It is now 15:36:01.291000

As you can see, the request sent at 15:35:54 is not yet complete, but Chrome is sending another one, resulting in 2 requests server side (that can create issues, duplicates, etc).

2. With HTTP => HTTPS enabled in the global vhost configuration

# Apache logs
[24/May/2024:15:53:25] 1.2.3.4 - www.example.com:443 "GET /testing HTTP/1.1" 200 "www.example.com/testing" bytes:34 time:4244717
[24/May/2024:15:53:28] 1.2.3.4 - www.example.com:443 "GET /testing HTTP/1.1" 200 "www.example.com/testing" bytes:34 time:4040528
[24/May/2024:15:53:32] 1.2.3.4 - www.example.com:443 "GET /favicon.ico HTTP/1.1" 200 "www.example.com/favicon.ico" bytes:0 time:364

# PHP logs
[2024-05-24 15:53:25.953574] 1.2.3.4 local.INFO: [REQUESTED_AT_15:53:25.948300] [https://www.example.com/testing] Request received, now I will wait 4 s
[2024-05-24 15:53:28.739584] 1.2.3.4 local.INFO: [REQUESTED_AT_15:53:28.738700] [https://www.example.com/testing] Request received, now I will wait 4 s
[2024-05-24 15:53:29.954046] 1.2.3.4 local.INFO: [REQUESTED_AT_15:53:25.948300] [https://www.example.com/testing] Done, I waited 4 s! It is now 15:53:29.954000
[2024-05-24 15:53:32.740055] 1.2.3.4 local.INFO: [REQUESTED_AT_15:53:28.738700] [https://www.example.com/testing] Done, I waited 4 s! It is now 15:53:32.739900

Here is a MRE:

• Open a Chromium-based browser
• Open dev tool on Network tab
• paste your “slow” URL, without http:// nor https:// (ex: www.example.net/)
• press Enter, and confirm the behavior:
  • first request sent
  • then after 3s, the browser cancels it, and requests another one

(It’s Laravel code but it’s the same with regular vanilla PHP of course)

<?php 
Route::get('/testing', function () {
    $u = url()->full();
    $s = 4;

    $now = DateTime::createFromFormat('U.u', microtime(true));
    $t = $now->format("H:i:s.u");
    Log::info("[REQUESTED_AT_$t] [$u] Request received, now I will wait $s s");

    sleep($s);

    $now = DateTime::createFromFormat('U.u', microtime(true));
    $t2 = $now->format("H:i:s.u");
    Log::info("[REQUESTED_AT_$t] [$u] Done, I waited $s s! It is now $t2");

    echo "Page loaded, OK";
});

As described here, you might reproduce this issue without an actual “slow” URL, just by throttling your connection speed.