Issue with migration

is it something to do with:

define('PERCH_PATH', str_replace(DIRECTORY_SEPARATOR.'config', '', dirname(__FILE__)));
define('PERCH_CORE', PERCH_PATH.DIRECTORY_SEPARATOR.'core');

in my config file?

I did yes, I have two other perch CMS's installed on the same server.

this is diagnostic report:

Perch: 2.8.14, PHP: 5.4.42, MySQL: mysqlnd 5.0.10 - 20111026 - $Id: c85105d7c6f7d70d609bb4c000257868a40840ab $, with PDO
Server OS: Linux, cgi-fcgi
Installed apps: content (2.8.14), assets (2.8.14), categories (2.8.14), perch_events (1.8), perch_news (3.7.6), perch_backup (1.2)
App runtimes: <?php include(PERCH_PATH.'/core/apps/content/runtime.php'); include(PERCH_PATH.'/addons/apps/perch_blog/runtime.php'); include(PERCH_PATH.'/addons/apps/perch_events/runtime.php'); include(PERCH_PATH.'/addons/apps/perch_news/runtime.php'); ?>
PERCH_LOGINPATH: /perch
PERCH_PATH: /var/sites/l/lovebedford.co.uk/public_html/perch
PERCH_CORE: /var/sites/l/lovebedford.co.uk/public_html/perch/core
PERCH_RESFILEPATH: /var/sites/l/lovebedford.co.uk/public_html/perch/resources
Image manipulation: GD
PHP limits: Max upload 100M, Max POST 100M, Memory: 128M, Total max file upload: 100M
Resource folder writeable: Yes
DOCUMENT_ROOT: /var/sites/l/lovebedford.co.uk.gridhosted.co.uk/public_html
HTTP_HOST: lovebedford.co.uk.gridhosted.co.uk
REQUEST_URI: /perch/core/settings/diagnostics/
SCRIPT_NAME: /perch/core/settings/diagnostics/index.php

Bear in mind this is for lovebedford.co.uk.gridhosted.co.uk which is a 'preview' of my site, because obviously I've not changed the DNS etc. of lovebedford.co.uk yet.

It is only pages that use the /pages that are failing.

e.g. this works OK (minus the error at the top): https://lovebedford.co.uk.gridhosted.co.uk/news/

I just develop on the server rather than locally.

It's a Linux server, same as the other two Perch sites I have hosted if that helps.

As well as migrating the site, I'm also upgrading from Perch 2.3 to the most recent, if that would make any difference.

I have never worked locally I'm afraid, don't know how to do it. I have contacted my host to see if there's anything stopping it not working as I guess it must be down to the PHP include...