Unable to view/edit entries in xreceiver module

When trying to view entries in xreceiver, there is a HTTP 500 error

The site is for an old client.

Entry links are: https://[client url]/cms/addons/apps/tfd_xreceiver/edit/?id=add

Perch diagnostic as follows:

PERCH INFORMATION
Perch: 2.8.15
Production mode: Production (100)
Installed apps: content (2.8.15), assets (2.8.15), categories (2.8.15), perch_blog (5.0), perch_events (1.9.2), perch_forms (1.8.3), tfd_xreceiver (2.1)
DB driver: PDO
DB tables: perch2_blog_authors, perch2_blog_comments, perch2_blog_index, perch2_blog_posts, perch2_blog_posts_to_tags, perch2_blog_sections, perch2_blog_tags, perch2_blogs, perch2_categories, perch2_category_counts, perch2_category_sets, perch2_content_index, perch2_content_items, perch2_content_regions, perch2_events, perch2_events_categories, perch2_events_to_categories, perch2_forms, perch2_forms_responses, perch2_my_sample_things, perch2_navigation, perch2_navigation_pages, perch2_page_templates, perch2_pages, perch2_resource_log, perch2_resource_tags, perch2_resources, perch2_resources_to_tags, perch2_settings, perch2_user_passwords, perch2_user_privileges, perch2_user_role_privileges, perch2_user_roles, perch2_users, perch2_xreceiver_listings
Users: 4
App runtimes:
<?php
    $apps_list = array(
        'content', 
        'categories',
        'perch_blog',
        'perch_forms',
        'perch_events',
        'tfd_xreceiver'
    );
Scheduled tasks for perch_blog: delete_spam_comments (1440 mins)
Scheduled tasks for perch_events: update_category_counts (60 mins)
Editor plug-ins: markitup
H1: b5268bc07153b8d502e0805eac6d494e
L1: 730016cb1044393f92311f663291f567
headerColour: #ffffff
content_singlePageEdit: 1
helpURL:
siteURL: /
hideBranding: 0
content_collapseList: 1
lang: en-gb
update_2.8.15: done
latest_version: 2.8.15
on_sale_version:
perch_blog_update: 5.0.1
perch_blog_post_url: /news/post.php?s={postSlug}
headerScheme: light
perch_blog_site_name:
perch_blog_slug_format: %Y-%m-%d-{postTitle}
perch_blog_akismet_key:
perch_blog_max_spam_days: 0
dashboard: 1
hide_pwd_reset: 0
content_hideNonEditableRegions: 0
content_frontend_edit: 0
perch_blog_comment_notify: 0
perch_events_update: 1.8
perch_events_detail_url: /news/events/event.php?s={eventSlug}
update_2.8.34: done
PERCH_DEVELOPMENT: 10
PERCH_STAGING: 50
PERCH_PRODUCTION: 100
PERCH_DB_USERNAME: infosec_tfd
PERCH_DB_SERVER: localhost
PERCH_DB_DATABASE: admin_infosecDB
PERCH_DB_PREFIX: perch2_
PERCH_TZ: UTC
PERCH_EMAIL_FROM: jamesh@thirdfloordesign.co.uk
PERCH_EMAIL_FROM_NAME: James Holmes
PERCH_LOGINPATH: /cms
PERCH_PATH: /var/www/vhosts/infosecpeople.co.uk/httpdocs/cms
PERCH_CORE: /var/www/vhosts/infosecpeople.co.uk/httpdocs/cms/core
PERCH_RESFILEPATH: /var/www/vhosts/infosecpeople.co.uk/httpdocs/cms/resources
PERCH_RESPATH: /cms/resources
PERCH_HTML5: 1
PERCH_RUNWAY:
PERCH_ERROR_MODE: DIE
PERCH_DATE_LONG: %d %B %Y
PERCH_DATE_SHORT: %d %b %Y
PERCH_TIME_SHORT: %H:%M
PERCH_TIME_LONG: %H:%M:%S
PERCH_DEBUG:
PERCH_PREVIEW_ARG: preview
PERCH_TEMPLATE_PATH: /var/www/vhosts/infosecpeople.co.uk/httpdocs/cms/templates
PERCH_DEFAULT_DOC: index.php
PERCH_DEFAULT_EXT: .php
PERCH_PRODUCTION_MODE: 100
PERCH_RWD:
PERCH_HTML_ENTITIES:
PERCH_SSL:
PERCH_STRIPSLASHES:
PERCH_PROGRESSIVE_FLUSH: 1
PERCH_AUTH_PLUGIN:
PERCH_DB_CHARSET: utf8
PERCH_DB_PORT:
PERCH_DB_SOCKET:
PERCH_SESSION_TIMEOUT_MINS: 20
HOSTING SETTINGS
PHP: 5.4.13
Zend: 2.4.0
OS: Linux
SAPI: cgi-fcgi
Safe mode: not detected
MySQL client: 5.5.30
MySQL server: 5.5.30
Extensions: Core, date, ereg, libxml, openssl, pcre, zlib, bz2, calendar, ctype, hash, filter, ftp, gettext, gmp, SPL, iconv, pcntl, readline, Reflection, session, standard, shmop, SimpleXML, sockets, mbstring, tokenizer, xml, cgi-fcgi, curl, dom, fileinfo, gd, imagick, imap, json, ldap, exif, mcrypt, mysql, mysqli, odbc, PDO, pdo_mysql, PDO_ODBC, pdo_sqlite, Phar, snmp, sqlite3, wddx, xmlreader, xmlrpc, xmlwriter, xsl, zip, mhash, ionCube Loader
GD: Yes
ImageMagick: Yes
PHP max upload size: 128M
PHP max form post size: 8M
PHP memory limit: 128M
Total max uploadable file size: 8M
Resource folder writeable: Yes
Session timeout: 24 minutes
Native JSON: Yes
Filter functions: Yes
Transliteration functions: No
PATH: /sbin:/usr/sbin:/bin:/usr/bin
PP_CUSTOM_PHP_INI: /var/www/vhosts/system/infosecpeople.co.uk/etc/php.ini
PP_CUSTOM_PHP_CGI_INDEX: fastcgi
SCRIPT_NAME: /cms/core/settings/diagnostics/index.php
REQUEST_URI: /cms/core/settings/diagnostics/?extended
QUERY_STRING: extended
REQUEST_METHOD: GET
SERVER_PROTOCOL: HTTP/1.0
GATEWAY_INTERFACE: CGI/1.1
REMOTE_PORT: 40426
SCRIPT_FILENAME: /var/www/vhosts/infosecpeople.co.uk/httpdocs/cms/core/settings/diagnostics/index.php
SERVER_ADMIN: jamesh@thirdfloordesign.co.uk
DOCUMENT_ROOT: /var/www/vhosts/infosecpeople.co.uk/httpdocs
REMOTE_ADDR: 82.35.54.156
SERVER_PORT: 443
SERVER_ADDR: 205.186.165.244
SERVER_NAME: www.infosecpeople.co.uk
SERVER_SOFTWARE: Apache
SERVER_SIGNATURE: <address>Apache Server at www.infosecpeople.co.uk Port 443</address>
HTTP_COOKIE: _ga=GA1.3.215406947.1536154169; _gid=GA1.3.1785597421.1536154169; PHPSESSID=66egu62u0ej9knrka6m9k6f9c2; cmsa=1
HTTP_ACCEPT_LANGUAGE: en-US,en;q=0.9
HTTP_ACCEPT_ENCODING: gzip, deflate, br
HTTP_REFERER: https://www.infosecpeople.co.uk/cms/core/settings/diagnostics/
HTTP_ACCEPT: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8
HTTP_USER_AGENT: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36
HTTP_UPGRADE_INSECURE_REQUESTS: 1
HTTP_CONNECTION: close
HTTP_X_ACCEL_INTERNAL: /internal-nginx-static-location
HTTP_X_FORWARDED_FOR: 82.35.54.156
HTTP_X_REAL_IP: 82.35.54.156
HTTP_HOST: www.infosecpeople.co.uk
HTTPS: on
UNIQUE_ID: W4-hus26pfQAAHlFhKwAAAAA
FCGI_ROLE: RESPONDER
PHP_SELF: /cms/core/settings/diagnostics/index.php
REQUEST_TIME_FLOAT: 1536156090.7687
REQUEST_TIME: 1536156090