Support » Plugin: Smush Image Compression and Optimization » update can cause admin-ajax.php 404 issue

  • Resolved helloadorable


    Hello. We upgraded to yesterday an noticed a strange side effect. Whenever we tried to use the Add Media box, all of the text boxes for caption description etc were missing.

    When we looked at the browser debugging tool, it was showing a 404 error for wordpress’s admin-ajax.php on the first attempt but then success on multiple attempts. This happened in multiple browsers. I believe this initial 404 error was causing all those text boxes to not appear.

    So we deactivated Smush and all is well again (no 404 error for admin-ajax and the text boxes show fine). But we’d love to be able to use Smush again if this issue could be fixed somehow.

    I’d be curious if this is happening to anyone else.

Viewing 4 replies - 1 through 4 (of 4 total)
  • helloadorable


    I also noticed that the headers for when admin-ajax.php was called the very first time (when the 404 error happens) were slightly different than the way admin-ajax.php was called subsequent times (when the successful 200 status happens).

    One difference I noticed was this line:
    “content-encoding: br”

    I have no idea what this means or if it’s helpful. Just happened to notice it when I was trying to figure out why admin.ajax.php was giving a 404 error.

    Plugin Author Umesh Kumar


    Heya @helloadorable,

    Thanks for sharing the detailed information about the issue. I can’t really think of a reason for Smush causing issue with admin-ajax.php so it might be possibly a conflict with other plugin.

    Would it be possible for you to deactivate all other plugins and just run Smush and see if the problem persists?

    Another option is to re-install the plugin, just to make sure that it is updated properly.

    Also, if you could check for any errors in browser console and maybe you can use Query Monitor plugin to check for any other errors.

    Let me know how it goes.

    Thanks, Umesh



    Thanks for the reply Umesh. You’re right that it might be some other plugin causing a conflict. When I have time, I’ll hunt it down some more and report back.

    Plugin Support Dimitris – WPMU DEV Support


    Hello @helloadorable

    It’s been a while since we’ve heard back from you, so I’m marking this topic as resolved. Feel free to post back any feedback you have and we’ll be happy to reopen it and carry on with troubleshooting. 🙂

    Warm regards,

Viewing 4 replies - 1 through 4 (of 4 total)
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