Incompatibility with Custom Sidebars Pro and Events Manager Pro.

We have found an incompatibility with your plugin version and Events Manager Pro. The problem stems from your code in inc/class-custom-sidebars-explain.php and inc/external/wpmu-lib/functions-wpmulib.php, namely:

if ( ! session_id() ) {



This somehow interferes with the shopping cart function Events Manager Pro. Commenting out the above code fixes the problem and seems to have no adverse effect on using Custom Sidebars Pro

Can you tell me why this code is needed?

  • Vaughan

    Hi @Catfish,

    It should be detecting if a session exists, and is used on the front end in the following functions (for explain.php)

    public static function do_explain() {
    		return 'on' == @$_SESSION['cs-explain'];
    	 * Sets the explain state
    	 * @since
    	 * @param string $state [on|off]
    	public static function set_explain( $state ) {
    		if ( $state != 'on' ) {
    			$state = 'off';
    		$_SESSION['cs-explain'] = $state;

    for the other file, it looks like it's for persistant sessions, whilst a user is browsing the site, so it stores their choices if they open/close or other sidebar related stuff. I can't give an exact explanation on exactly what. Let me just ask one of our developers to see if he can answer your question more precisely and in better detail.


  • Jose

    Hey @Catfish,

    Hope you are doing well today!

    This sounds weird. The check for an existing session ID is there to avoid resetting other existing sessions.

    Reading into the changelog of Event Manager, I noticed that they already had a conflict with session_start():

    = 5.1.8 =
    * fixed jigoshop session_start conflict

    They might be handling the session in a weird fashion. Did you already contact the plugin authors?

    I'm calling the lead developer @Philipp Stracker to get his opinion, maybe I'm missing something.

    Thanks for your patience here.


  • Philipp Stracker

    What is the issue with the Events Manager Pro plugin? I.e. what is not working?

    Those two files you mentioned use the $_SESSION scope to save some session-related data (flags, notifications for the user). Commenting out this code might not have an affect when the Events Manager Pro is activated, since your plugin possibly also starts the session (and thus our plugin will find a valid session once it is needed). Also the session is not used on every request, but mostly on the admin side

  • Catfish

    Hi Phillip,

    Sorry for the delay in getting back to you. This issue arose from our programmer, who is not a member of WPMU DEV, so I am conveying her messages to you.

    She wrote:

    "i can't reply to that forum so you should reply and refer him to:

    telling him that the behaviour with custom sidebars pro is exactly the same as with wp stylesheet switcher."

    Hope that's clear.



  • Philipp Stracker

    Thanks for the response Bob!

    If your collegue cannot reply to this forum then it will be best if she gets in touch with us directly by using the contact form:

    Choose "I have a different question"
    Subject "Attn: Philipp Stracker"
    In the message include a link to this forum thread so other support people know what it's about (you can send her the link)

    However, generally removing the session function from our plugins does not seem like an appropriate solution. I am quite certain that it is possible to get the Events Manager Pro plugin to work together with our plugin, and I'd love to help debugging and solving this issue!

    Also please describe how we can reproduce the issue - I installed the free version of the plugin ( but was not able to reproduce any issue. In fact I did not see any shopping cart. What I did:
    Install and activate the plugin, create a demo event with Registration enabled. Then I visit the event page and register for it; this was done without showing a shopping cart... Possibly I did it wrong :wink:

    Thanks, Philipp

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