Possible Serious PHP Error?

[HM666]

I'm getting this error whenever I try to refresh in the CMS or when I click on various links in the CMS sidebar menu.

1. I'm using the built in vBulletin sidebar CMS menu, recent posts & threads widgets in the CMS for testing purposes.

2. I'm using vB 4.2.5 Suite.

3. Running PHP version 7.1.32

4. Using MySQL 5.0.12 (MySQLi)

5. Its a fresh install and I'm using the default style.

6. There are plugins & mods installed. I disabled them globally and tried again and still get the same error. So I do not believe that its a mod that I've installed.

7. I also have an issue with the Mod_Security at times in various places on the site.

Not Acceptable!
An appropriate representation of the requested resource could not be found on this server. This error was generated by Mod_Security.

Here is the error I get:

Call to undefined function fetch_phrase_group() on line 196 in /home/xxxxx/public_html/xxxxx/packages/vbcms/widget/activitystream.php
#0 /home/xxxxx/public_html/xxxxx/packages/vbcms/widget/activitystream.php(172): vBCms_Widget_ActivityStream->getStream()
#1 /home/xxxxx/public_html/xxxxx/packages/vbcms/controller/content.php(237): vBCms_Widget_ActivityStream->getPageView()
#2 /home/xxxxx/public_html/xxxxx/vb/controller.php(261): vBCms_Controller_Content->actionView()
#3 /home/xxxxx/public_html/xxxxx/packages/vbcms/route/content.php(97): vB_Controller->getResponse()
#4 /home/xxxxx/public_html/xxxxx/vb/router.php(251): vBCms_Route_Content->getResponse()
#5 /home/xxxxx/public_html/xxxxx/vb/bootstrap.php(58): vB_Router::getResponse()
#6 /home/xxxxx/public_html/xxxxx/content.php(30): require_once('/home/xxxxx...')
#7 {main}

Line 196ish activitystream.php:

	/*
	 * Fetch the stream data!
	 */
	private function getStream()
	{
		global $vbphrase;

		fetch_phrase_group('activitystream');

		$activity = new vB_ActivityStream_View_Block($vbphrase);
		return $activity->process($this->config);
	}

	/**
	 * Gets a cache key - each user has a cache due to complicated permissions
	 * 	 
	 * @param  boolean $widgetid - Added for PHP 5.4 strict standards compliance
	 * @param  boolean $nodeid   - Added for PHP 5.4 strict standards compliance
	 *
	 * @return string
	 */

Is this possibly a PHP 7.1 issue I'm having or is it something else?