Causing 500 Internal Server errors

  • Hi gang! First off, let me say that I’ve enjoyed using your plugin (I replaced Yoast SEO with yours). However, in recently trying to diagnose problems with receiving 500 internal server errors, I disabled all plugins, and then activated them one-by-one to diagnose if it was a plugin causing the problem. I found three plugins that were causing the problems.

    1. Forminator (a forms plugin); problems occurred when activated, stopped when deactivated; solution: Deleted plugin
    2. Chaty (a press to call for mobile plugin); problems when active, stopped when deactivated; solution: deleted plugin
    3. Rank Math SEO (free version); I was really hoping this wouldn’t be another plugin causing the problem, but I noticed two things. The site edit pages and previews were slowed down considerably after re-activating the Rank Math plugin, and on the 4th attempt to preview a page, I received an internal server error. I then received several within 5 minutes, and after deactivating the plugin, I haven’t received any. I wound up deleting the plugin. I’m simply writing to let you know that (at least in my case) your plugin was caused 500 internal server errors.

    For information, the site I design is hosted by Hostgator on their Optimized WordPress Hosting Plan using 5.6, and with PHP 7.4 installed. 256 MB RAM, and 25 process limit. I have other plugins installed which could have created conflicts perhaps, but only three plugins caused the internal server errors, and unfortunately RankMath was one of them.

    Sorry…but I thought you might be interested.

    If I can be of any further help, please let me know.


Viewing 14 replies - 16 through 29 (of 29 total)
  • Hello,

    Sorry for the delay, and thank you for the additional information.

    5xx errors are usually related to the server, so it’s also possible that your host might not have allocated enough resources for your site too, considering it’s happening when the other 2 plugins you have mentioned were activated. Could you please also check if setting these PHP values would fix the issue?

    PHP Memory Limit: 512M
    Max input time: 150
    PHP time limit: 120
    PHP max input variables: 1000

    If the issue persists, we may need to investigate this further as we couldn’t replicate the error on our end. Please also include a WordPress and FTP logins in the designated Sensitive Data section.

    I hope that helps. Thank you, and we really look forward to helping you.

    Hello Dave,

    Sorry for the confusion.

    I wanted to add that given the issue is currently only on your site, could you try creating a duplicate staging site of your production site and check you can replicate the issue. If you are able to replicate this, edit and include the Staging site & FTP logins in the designated Sensitive Data section so we can look into this further from our end.

    Looking forward to helping you.

    I have the same problem recently. The error is Internal Error (error 500). I checked all plugins, only when I deactivate Rank Math (free version), my website can be updated. Whenever I activate Rank Math, the error occur and I couldn’t update my content. Please check and see how it can be solved.


    Thanks for your input. Do you mind if I ask whether you have your website hosted with Hostgator??? I’m working with HG’s tech support team to try and figure out whether there’s a conflict going on somewhere on their server.

    By the way, for RankMath tech support, I’ve been checking the DEBUG.LOG info and there are a couple interesting entries that are appearing regularly. They have to do with hg_manage.php file, which is used exclusively by Hostgator.

    These are the errors:

    [14-Jan-2021 18:35:08 UTC] PHP Notice: ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush in “sitename”/public_html/hg_manage.php on line 400, (which is highlighted below):

    Pasted from hg_manage.php file:

    * Present the output
    public function __destruct() {
    ob_end_flush(); <—–LINE 400

    Also referenced here:
    [14-Jan-2021 19:13:30 UTC] PHP Notice: Trying to get property ‘ID’ of non-object in “sitename”/public_html/hg_manage.php on line 607, (which is highlighted below):

    Pasted from hg_manage.php file:

    * This will fetch the first admin user from the db. as the WP user class
    * Or it will throw an UnderflowException
    * @throws UnderflowException
    * @return Closure
    private function _fetch_first_admin_user()
    $found_user = array_reduce(
    function($carry, $item){
    return ($item->caps[“administrator”] && (($carry->ID ?: 99999999999 ) > $item->ID)) ? $item : $carry; <—-LINE 607
    return $found_user ?: function() { throw new \UnderflowException(); };

    I don’t know if either of those errors would cause the internal error issue or not? Also, Hostgator said that since I’m on their Optimized WordPress hosting plan, and do not have access to cpanel, there’s no way to set up a separate staging site. I did find a plugin that may allow a staging site to be set up in a folder instead of a subdomain, so maybe that will work??


    Found something interesting!!!

    But first, I have no idea what Yumna is talking about above. Looks like some sort of spam messaging?? Maybe you guys can delete those?

    Anyway, I tried an experiment this afternoon, and came up with an interesting discovery.

    I de-activated all of my plugins except for WP-Bakery, and RankMath SEO to try and isolate where the conflict is that triggers the 500 internal server errors. Was it with the theme itself? Or Wp-Bakery? Or what?

    So I did an experiment, and when only the theme, plus WP-Bakery, and RankMath SEO were activated, I wasn’t getting any errors. I thought, okay, now THAT’S interesting! It definitely pointed to a conflict with another plugin, so I kept RankMath SEO activated, and one-by-one enabled other plugins to see what happened.

    And, I found it!

    There’s a plugin that came bundled with my theme (The7 theme from Dream Themes). The bundle is called Ultimate Add-Ons for WP-Bakery from Brainforce that provides a ton of various design components to “beautify” your site, and add more functionality. From special heading formatting, to countdown timers, to flip boxes, to FAQ’s, to image carousels, etc. BUT…when THAT plugin and RankMath SEO are both enabled at the same time….I get the 500 Internal Server errors. If I keep only one active, and disable the other, no errors. It doesn’t matter which one remains active, and which one is disabled….no errors occur if only one of them is active. But when BOTH are enabled, the errors occur.

    Obviously, there’s a conflict between the two plugins.

    I left a message for the developers at Brainforce to see if they have any suggestions, and will keep you posted. Also, please let me know if this gives you guys any ideas as to what kind of conflict might be causing the internal server errors to occur when previewing from the edit page.



    Hi Dave,

    Thank you for the follow up details.

    We are glad to see positive progress on the issue.

    Could you please confirm when the plugin causing the issue was last updated? Has it been tested with the latest version of WordPress?

    If you could also share the plugin link, we can install and test if we can replicate the error from our end.

    We also look forward to hearing the response from the plugin team.

    Thank you

    The second link above accidently included the word “they” in it. Here’s the link to their website, but the first link above is to the actual bundle I’m using:



    Thank you for sharing the links.

    Let us know if they find anything that can help resolve this or if they have any related inquiries for us.

    We are here to assist you.

    Thank you


    Since this is a paid plugin, we are not able to check this from our end.

    Can you please share your WP logins so we can take a closer look at this issue?

    We look forward to helping you.


    We managed to get our hands on the plugin and tested it on our local setup and we added modules from VC addon plugin using VS Page builder.

    Everything seems to be working fine. Here is a screencast:

    Please let us know.


    I just watched your video from the link above, and I appreciate your follow up.

    HOWEVER, I’ve explained several times that the internal server errors occur only when I click the “Preview Changes” button in the top right corner above the blue “Update” button. I saw in your video that you were making edits on the page without any problems. I am able to do that too. I never get an error when I’m simply editing a page. It’s only when I click the “Preview Changes” button that the internal server error occurs (it doesn’t matter whether I make any changes to the page or not).

    Perhaps you can record a new video, load a page (you don’t have to make any edits on the page, as it’s not the edit that triggers the error), just load the page, and click the “Preview Changes” button. If you don’t get an error, then load a different page and do the same thing. It may take 3-4 pages before it triggers the error, as it doesn’t happen every time, but once the error is triggered, it will then start happening more frequently. Not every time, but once triggered, it will then happen 75% of the time.You can click the blue “Update” button if you want, but it’s not necessary. The errors occur whether you update the page or not….and again only occur when I click the “Preview Changes” button.

    Note that the only Elements I have turned on in the Ultimate Add-Ons plugin are:

    Info Boxes
    Advanced Carousel
    Fancy Text
    Image Separator
    Expandable Section
    Row Backgrounds

    You can turn these on or off under the Ultimate>elements menu. Turn on the above elements if they aren’t already selected, and perhaps make sure that those elements are used on a sample page. It may turn out to be that one of those elements is the cause of the error and not the entire Ultimate Add-Ons plugin?? I have the above elements used on almost every page of our website.



    I just re-read my original posts, and realized that I may not have brought up that the internal server errors only happen when clicking on the Preview Changes” button (until my last reply).

    I very sorry about that!! I’ve been communicating with Hostgator’s tech support, and had mentioned the “Preview Changes” button causing the errors, and I guess I thought I had covered that here also.

    So just to be clear, as mentioned in the post above, the internal server errors only happen when clicking on the “Preview Changes” button in the top right corner of the WordPress edit page screen. It never happens while actually editing the page, nor when visiting the live website.

    Sorry for any confusion!!!



    I should also mention that when the error shows up after clicking “Preview Changes”, I can immediately click the “Preview Changes” button again, and the page will load just fine.


    Thank you for the details.

    Allow us to test this from our end and get back to you.

    Looking forward to helping you.



    I still couldn’t reproduce this issue on my setup. Here is a screencast:

    As you said, I added the modules from WP Bakery on a page and also previewed few pages. If you are getting an Internal Server error then WordPress will log the error in the debug.log or error_log file. Please try setting the value of WP_DEBUG, WP_DEBUG_LOG constants to true and check the debug.log file for the error details.

    The error code you added in the Sensitive Data Section is not from the Rank Math plugin. So if that is the error you get after previewing a page then please get in touch with the Flipbook for VC plugin author.

    Looking forward to helping you.

Viewing 14 replies - 16 through 29 (of 29 total)

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