PHP Fatal error: ob_end_flush(): After updating to 6.8

  • bobsled

    (@bobsled)


    1 year, 1 month ago

    I have discovered an issue on one of my sites that has two subfolder sites.

    siteA.com -siteA.com/othersite – siteA/another site.

    Whenever I try to open the customizer in these three sites, it goes to a white page and causes this error: PHP message: PHP Fatal error: ob_end_flush(): Cannot use output buffering in output buffering display handlers in /home/clients/

    After clearing all the caches and disabling all plugins, I discovered when activating the plugins one by one that the error is caused by the Wordfence and Yoast SEO plugins. (the plugins are on all three sites) When I deactivate these two, the customizer works normally.

    The setup of these three linked sites worked fine before 6.8. Has there been a change in 6.8 that could cause this error with subfolder sites?

    Or could it be a plugin issue? Worfence and Yoast are normally releiable and updated regularly, so I have my doubts.

    All my other sites that do not have subfolders work as expected with no errors or bugs after updating to 6.8.

    • This topic was modified 1 year, 1 month ago by bobsled.
Viewing 6 replies - 1 through 6 (of 6 total)
  • Moderator threadi

    (@threadi)

    1 year, 1 month ago

    You have already found out that 2 plugins are causing the problem. I can’t reproduce the problem with either of them. I would therefore rather guess that there is some other factor that is decisive for you. Which theme are you using? I tried the last classic theme TwentyTwentyOne.

    Otherwise, I would recommend that you contact their support forums to clarify this:
    https://wordpress.org/support/plugin/wordfence/
    https://wordpress.org/support/plugin/wordpress-seo/

    Thread Starter bobsled

    (@bobsled)

    1 year, 1 month ago

    I use the Astra Pro theme on all my sites. I’ve been in touch with Astra support, and they can’t locate the source of the issue.

    Interestingly, if I deactivate the Astra Pro plugin, the customizer works, even with Wordfence and Yoast activated.

    But this makes it tough to trace the source of the problem as it could be either a WP, theme or plugin problem, or more likely, a combination.

    These three sites are very old, and I only use them now for testing. So, it’s not a big deal and not worth investing a lot of time chasing.

    But before I updated to 6.8 I recall reading a post about an issue with subfolders and the white screen when opening the editor. But unfortunately, I can’t find it again now.

    So for now, if there are no known issues regarding subfolder sites in 6.8, I’ll let this slide and hope perhaps future updates may resolve the issue.

    Moderator threadi

    (@threadi)

    1 year, 1 month ago

    What exactly do you mean by “subfolder sites”? Are you referring to a multisite installation?

    You wrote above that the problem only seems to occur with your commercial Astra Pro in combination with the two plugins. Of course, I can’t reproduce this here, as I don’t have access to commercial products (see also forum guidelines). But you have already narrowed it down to the two plugins and the theme, which is why I don’t see WordPress as the cause. I am also not aware of any change in 6.8 that could cause this in the Customizer.

    Thread Starter bobsled

    (@bobsled)

    1 year, 1 month ago

    What exactly do you mean by “subfolder sites”?

    It’s three sites on the same domain. Eg,

    example.com/
    example.com/shop/
    example.com/help/

    But if you are not aware of any issues, like I said before, it’s not worth chasing this issue. I’ll work around it for the time being and wait on future updates.

    Ahir Hemant

    (@hemant-ahir)

    1 year, 1 month ago

    Hi @bobsled

    Use a Debug Log to Trace the Exact Trigger

    Make sure WP Debug is on, then check the wp-content/debug.log after triggering the error.

    Use this in wp-config.php:

    define('WP_DEBUG', true);
    define('WP_DEBUG_LOG', true);
    define('WP_DEBUG_DISPLAY', false);

    That log might tell you which file and function inside Wordfence or Yoast is calling ob_end_flush();

    Reach Out to Plugin Support (with this info)

    Wordfence and Yoast both take bugs seriously. Include:

    • That you’re using a subfolder setup
    • That this only affects sites after WP 6.8
    • The specific PHP error
    • That the issue is confirmed with only their plugins active

    They may release a fix or workaround soon.

    Thanks
    Ahir Hemant

    Thread Starter bobsled

    (@bobsled)

    1 year, 1 month ago

    Thanks @hemant-ahir

    Thanks for the tip. I’ll give a try and see if it can help me trace the issue.

Viewing 6 replies - 1 through 6 (of 6 total)

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