[4.0] Joomla hates root jail: errors when JPATH_ROOT is /

[bato3]

Steps to reproduce the issue

In some web-server configuration, when JPATH_ROOT is / Joomla don't work correctly:

1. replaces slashes in web assets: HTMLHelper::convertToRelativePath()
2. when is configured without mod_rewrite work only for main page, others render as 404

Expected result

<link href="/media/vendor/fontawesome-free/css/fontawesome.min.css?5.14.0" rel="stylesheet" />

2. index.php?option=com_content&view=article&layout=edit&id=841 -> http status 200

Actual result

<link href="/mediavendorfontawesome-freecssfontawesome.min.css?5.14.0" rel="stylesheet" />

2. /index.php?option=com_content&view=article&id=841 -> http status 404
   /841-article-title -> https status 200

System information (as much as possible)

Shared web hosting, with domain connected to directory "with site separation".

(Provider: home.pl is one of the largest service providers in Poland.)

Additional comments

I had no problem with reconfiguration the server, but it took me a long time to find the problem. (And a lot of stress)

If this problem cannot be quickly dealt (HTTP 404), I suggest add warning to installator, admin and site .

if(JPATH_ROOT == '/installation' || JPATH_ROOT == '/administrator' || JPATH_ROOT == '/')

[SharkyKZ]

Can you check if PR #23149 fixes the issue?

[bato3]

This change JPATH_ROOT don't work:

define('JPATH_ROOT', JPATH_BASE === DIRECTORY_SEPARATOR?'':implode(DIRECTORY_SEPARATOR, $parts));

The test could show false results, I am not able to check it closely. I only have the live version.

If this help: Joomla 3.6 works on this configuration, but i can't update it to 3.9.

[SharkyKZ]

That's not the change in #23149.

[richard67]

@bato3 Please test the complete change from #23149 on 3.9, not only that one line. Could you do that? Thanks in advance.

[bato3]

@richard67 I have this issue for Joomla 4.0.

I have no way to test for v.3.9

[N6REJ]

@bato3 why can't you test on 3.9?

[bato3]

@N6REJ Because I only have one available place where I can check it and it's occupied by Joomla 4.0. And it's a live version.

You know it: All developers have test environments and some even have production environments.
My provider is an asshole. Doing something non-standard there is a pain. (but gives a lot of space for mail).

[N6REJ]

using 4.0 for a production site is not a wise move imo.