Support » Plugin: Crelly Slider » Incompatibility with aThemes Sydney Pro’s Customizer

  • Resolved doffine


    Hey @fabiorino,

    we just noted a problem with Crelly Slider on the Customizer page of (at least) aThemes’ “Sydney Pro” theme.

    When we try to load this theme’s customizer page we get a white screen with the following PHP warning:

    Warning: Cannot modify header information - headers already sent by (output started at /[SERVERPATH]/wp-content/plugins/crelly-slider/wordpress/admin.php:188) in /[SERVERPATH]/wp-admin/customize.php on line 126

    And then it depends on the PHP version if…

    a) PHP 5.6, 7.0, 7.1, 7.2: the customizer gets loaded anyway and overlays the warning so the message isn’t visible anymore


    b) PHP 7.3: the screen stays white and only shows the PHP warning.

    In case b) if you press F5 to reload the page then again a white page loads with the PHP message but the customizer’s HTML seems to be loaded without any CSS or something looking like that. The page is totally screwed up then.

    If we disable the Crelly Slider plugin then all is fine – even in PHP 7.3.

    What can we do?

    PS: WordPress is 5.3.2, MySQL is 5.7.28, Crelly Slider is 1.3.5, Sydney Pro is 2.0.15 (latest version)

    Many greetings,
    – doffine

Viewing 6 replies - 1 through 6 (of 6 total)
  • Plugin Author Fabio Rinaldi


    I can’t reproduce the problem locally running PHP 7.3.1 and WordPress 5.3.2 with the default Twenty Nineteen theme.

    That said, I might know what’s going on: take a look at the Crelly Slider code, line 196
    I’m probably using the wrong WP hook (admin_enqueue_scripts instead of admin_head) to inject the code starting at line 188.

    May I ask you to help me figure out if that’s actually the problem? You just have to edit that file on your server and change the string “admin_enqueue_scripts” to “admin_head”. If you need help to do that, I’ll be happy to give you a hand.
    Once the modification is done, refresh the page and the error should disappear.

    If you can’t help me test the patch, or the fix doesn’t work, I’ll try to investigate the problem more accurately, but that’ll require some time.

    Hey @fabiorino,

    thank you so much for coming back so quickly. I just tested the changes as suggested and you are right: That was it! After changing the hook in both occurences in /crelly-slider/wordpress/admin.php the error was gone. It was not sufficient only to change the first occurence.

    So I changed in line 196 and in line 281 “admin_enqueue_scripts” to “admin_head” and that together ended the problem.

    Will you publish an update with this fix?

    Thanks again for helping with this problem!

    Plugin Author Fabio Rinaldi


    Hi, well spotted! Nice to know it works, I’ll release a fix ASAP

    Hey @fabiorino,

    great – many thanks for the perfect support!


    Plugin Author Fabio Rinaldi


    Hi, I’ve just released Crelly Slider 1.3.6 which includes the fix discussed in this thread. You should be able to upgrade the plugin with the standard update procedure from your WordPress admin panel.


    Hey @fabiorino,

    we just updated to 1.3.6 and voilĂ  – the problem is fixed! Thank you very much again!


Viewing 6 replies - 1 through 6 (of 6 total)
  • You must be logged in to reply to this topic.