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EventSource's response has a MIME type ("text/html") that is not "text/event-stream". Aborting the connection. header is set to text/event-stream

Hi I get This error in my console using sse

EventSource's response has a MIME type ("text/html") that is not "text/event-stream". Aborting the connection.

js code is :

if (typeof(EventSource) !== "undefined") 
    var source = new EventSource("../api/updateWellData.php?uid=<?php echo $node_id ?>");
    source.onmessage = function(event) {
        var response = JSON.parse(event.data);
        document.getElementById("result").innerHTML = response.test;
        // some code like the above line
    // refresh the page every 30 secs
The PHP Code is :
header('Cache-Control: no-cache');
header("Access-Control-Allow-Origin: *");
header("Content-Type: text/event-stream");
require_once("../resources/config.php");
if (isset($_GET['uid']))
    $uid = $_GET['uid'];
    while (1) 
        $query = Query("SELECT * FROM well_data_last WHERE well_detail_id = $uid");
        $result = fetch_array($query);
        echo json_encode($result);
        ob_end_flush();
        flush();
        sleep(1);
This is my first time using sse I used the following documents : mozilla | w3schools
                I am having same issue in laravel setup. Some solutions said remove white spaces in php. But that did not resolved my issue.
– Viral
                Apr 8, 2019 at 11:46
This error occurs when your PHP code outputs text in the wrong format.
This may be either a PHP error message (all of which are outputted as raw HTML), or some other text on the page which does not fit the text/event-stream format.
If the output of the PHP file does not match the format required by text/event-stream, it will fall back to using text/html. Javascript requires event streams use the text/event-stream content type so the JS console will show an error, but this is just a symptom of the actual problem - to fix the issue you need to fix your PHP.
In OP's case, the issue is with their echo statement. All data outputted to the stream must be proceeded by data:, and ended with a newline \n. The stream itself must end with another newline to indicate that no more data: messages follow.
To fix the error, OP should change
echo json_encode($result);
echo "data: " . json_encode($result) . "\n\n";
        
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