Updating XAMPP broke php web page execution

I use a windows 10 64-bit desktop and a windows 10 also 64-bit laptop. This has happened on both computers.

After doing a complete uninstall of an old version of XAMPP(in Admin account), I reinstalled the newest version (xampp-win32-7.3.1-0-VC15-installer.exe as an Admin with Firewall and virus protection disabled).

I verified the install by typing localhost/ into my Chrome brower and it came up with the XAMPP web page at localhost/dashboard.

I then loaded the db backup into phpMyAdmin 4.8.4. And I copied the backup folder of my pages into htdocs.

But now the php web pages that displayed correctly in the old version now throw this error on some pages, not all.

Warning: require_once(/includes/session.php): failed to open stream: No such file or directory in C:\xampp\htdocs\my_rabbits\my_profile.php on line 1

Fatal error: require_once(): Failed opening required '/includes/session.php' (include_path='C:\xampp\php\PEAR') in C:\xampp\htdocs\my_rabbits\my_profile.php on line 1

I checked the paths and they are all correct - no misspellings. My includes folder is in htdocs as is the individual my_profile.php page. Here is what line 1 looks like of my_profile.php page:

<?php require_once("/includes/session.php"); ?>

Here is what my includes/session.php code looks like:

<?php

   session_start();

   function message() {
      if (isset($_SESSION["message"])) {
         $output = "<div class=\"message\">";
         $output .= htmlentities($_SESSION["message"]);
         $output .= "</div>";

         // clear message after use
         $_SESSION["message"] = null;

         return $output;
      }
   }

   function errors() {
      if (isset($_SESSION["errors"])) {
         $errors = $_SESSION["errors"];

         // clear message after use
         $_SESSION["errors"] = null;

         return $errors;
      }
   }

?>

Thanks for any help you could give. I am a novice user and navigating in unknown waters...

include_path in php.ini - no current path

include_path = ".;C:\xampp\php\PEAR"