I tested this patch against my 4.4 app, and it fixes the issue mentioned in #47186

Pleas note that the problem also exists in newer Symfony versions, e.g.:

Should I open a separate ticket for forward ports?

As I do not understood how this change here is related to forward ports it seems indeed to be better to open a new issue that describes what you have in mind. :)

Sorry, I'm not sure is forward ports is actually a word, I meant it as the opposite of backports (because this is how you do in Symfony, right? You merge to the lowest branch and then you port forwards from there).

What I meant to say was the confusion between self::$kernel and static::$kernel also exists in newer branches, including 6.2. So the reproduction code in #47186 (or something similar) would also produce an error on these newer branches

Oh, I completely misunderstood your previous comment then. :) I was thinking in terms of forwarded ports when using an HTTP proxy. 😄 I have now merged everything up into the 6.2 branch.

Awesome, thanks!