Getting "An active PHP session was detected" critical warning in wordpress - wordpress

Question

A PHP session was created by a session_start() function call. This interferes with REST API and loopback requests. The session should be closed by session_write_close() before making any HTTP requests.

Answer 1

In most cases, the real reason of the above errors is the incorrect mechanism for using PHP sessions within plugins or themes when they are using the session_start() function.
Now you need to identify what plugin cause this issue by deactive your plugin one by one.
Then in that plugin, you need to find a piece of code similar to this:
if ( !session_id() ) {
session_start();
}
then change it to:
if ( !session_id() ) {
session_start( [
'read_and_close' => true,
] );
}
Then you are done. In most cases, this will fix the issue. Good luck!

Answer 2

Had the same issue due to WP Hotel Booking plugin use. I fixed it! Took me a while to find a plugin it caused and editing the plugin .php didn’t help. But I fixed it adding a snippet of code to functions.php of the CHILD theme:
function mymodule_curl_before_request($curlhandle){
session_write_close();
}
add_action( ‘requests-curl.before_request’,’mymodule_curl_before_request’, 9999 );
There's a background to this solution at: Make WordPress Core, Loopback request fails if headers set in curl
(Original link in German doesn't exist anymore and was referring to this other related discussion.)

Answer 3

Often this critical issue is caused by conflict in SESSION when using the PHP session_start() function.
For example I have used a Calculation plugin in Wordpress and after Wordpress version update this error occured.
So I detected the plugin which causes this issue as activated/deactivated plugins one by one.
SOLVING these errors: In File manager of my site I got the .php files of the plugin and searched for session_start() function. Where it was used after it I used this function in a row session_write_close();
Source of the function
Regards!

Answer 4

To chime in with my own experience here, this very issue was resolved by turning off the “cross sell pop up” module of Shopengine Pro. Indeed there’s a session start in the php. I have notified them about this today. Maybe it’ll help someone else meantime!

Answer 5

I found out that you get these critical health warnings when you install a plugin or a plugin Adon and fail to complete its setup to the end. So the simplest solution is to deactivate the plugin or complete the plugin set-up. My errors were caused by a Woocommerce Adon which I deactivated and when I refreshed the health status the two issues were gone. I hope this helps.

Answer 6

#David M., If the issue is specifically happening with the Cross-Sell Popup Module of the ShopEngine PRO plugin, then it can be fixed by adding a small piece of code on the cross-sell-popup.php file that will read and close the session of the Cross Sale Popup module immediately.
Big Thanks to #thống nguyễn for the solution.
On the line 18th, from where the session starts, replace the session_start() with the following code:
session_start([
'read_and_close' => true
]);
Hope it will help.

Answer 7

If you tried the above and it's not working try to change the php version from your hosting's CPanel
I had the same error ande i changed the php version from 7.4 to 7.3 and it all went well