I just read another post to this forum titled: Fatal error: Call to a member function get() on null in …/query.php on line 28
And I do also have Events Manager Pro and think that is their plugin causing the problem not yours, I am going to try to contact them and see if they know whats causing the issue.
Thank you for your response.
This is the error message that I get: The plugin participants-database/participants-database.php has been deactivated due to an error: Plugin file does not exist.
I have PHP version 5.4.43 installed on my website.