Bring your own theme to PHP 8

Question

My self-created theme no longer works under PHP 8. I would like to change it so that it continues to work. Currently only the navigation is displayed.

I have deactivated all plugins.

I have tried to solve this via the help page, but I can't find the error(s).

I have provided the theme as a ZIP.

I would be grateful for any help.

The page I need help with: https://www.johanneskroening.de/

Answer 1

I have found the error.

In the header.php an undefined constant was tried to be accessed. So instead of the following wrong code:

<?php if ($pagetitle == pagetitle_1){

  $pt1 = "pagetitle_1";

  $main = "main_1";

} else {

  $pt1 = "";

}

?>

I had to add the quotation marks to pagetitle:

<?php if ($pagetitle == "pagetitle_1"){

  $pt1 = "pagetitle_1";

  $main = "main_1";

} else {

  $pt1 = "";

}

?>