Error when editing data in database with mysql - php

Question

This is my code which shows current events and lets the user change the date, name or venue of the event.
I keep getting a 500 error for some reason. I think it is due to the information being passed to and from the database.
database set up is :userid ,eventname, venue, date, name ,eventid... respectivley
<div class="current events">
<h1>Your Current Events:</h1>
<?php
$sql = "SELECT * FROM events WHERE userid='{$_SESSION['u_id']}';";
$result = mysqli_query($conn, $sql);
if (mysqli_num_rows($result) > 0){
while ($row = mysqli_fetch_assoc($result)){
echo "<b>Event name: </b>";
echo " ";
echo $row['eventname'];
echo " ";
echo "<b>Event Venue: </b>";
echo " ";
echo $row['venue'];
echo " ";
echo "<b>Event Date: </b>";
echo " ";
echo $row['date'];
echo "
<form method='POST' action='editevent.php'>
<input type='hidden' name='eventname' value='" .$row['eventname']. "'>
<input type='hidden' name='venue' value='" .$row['venue']. "'>
<input type='hidden' name='date' value='" .$row['date']. "'>
<input type='hidden' name='name' value='" .$row['name']. "'>
<button>Edit</button>
</form>
";
}
}else{
echo "No Upcoming Events";
}
?>
</div>
I then have another file in my includes directory which allows changes to the information.
<?php
session_start();
if (isset($_POST['eventsubmit'])) {
$eventname = $_POST['eventname'];
$venue = $_POST['venue'];
$date = $_POST['date'];
$name = $_POST['name'];
$eventname = mysqli_real_escape_string($conn, $_POST['eventname']);
$venue = mysqli_real_escape_string($conn, $_POST['venue']);
$date = mysqli_real_escape_string($conn, $_POST['date']);
$name = mysqli_real_escape_string($conn, $_POST['name']);
$sql = "UPDATE events SET eventname='$eventname' WHERE userid='2' ";
mysqli_query($conn, $sql);
header("Location: ../members.php?event=success");
exit();
} else {
header("Location: ../signup.php");
exit();
}
}

Answer 1

I check your code in second php file you put one extra this } please remove it.

Answer 2

please use mysqli_error instruction to get exactly which error you get
mysqli_query($conn, $sql)or die( mysqli_error($conn));
or you can use to show php error if there any error in php syntax in start of page
error_reporting(E_ALL);
ini_set('display_errors', 1);