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Solved – Installation Failed / Deletion Failed in WordPress

Solved – Installation Failed / Deletion Failed in WordPress

Posted by Joseph Turley Technology

I was working on my website this morning and discovered that I was getting an error on a security scan of my website for a plugin that I have installed elsewhere and trust highly (Cloudflare). Looking into the error message a bit made me think that I should just uninstall and reinstall the plugin. I gave that a shot and interestingly enough, I found that I got an error message while removing the plugin. While it wasn’t Hello Dolly, it the error message looked like this.

Deletion failed: {“success”:true,”data”:{“delete”:”plugin”,”slug”:”hello-dolly”,”plugin”:”hello-dolly\/hello.php”,”pluginName”:”Hello Dolly”}}

deletionfailed

When I tried to reinstall the plugin, I got a similar message.

Installation failed: {“success”:true,”data”:{“install”:”plugin”,”slug”:”hello-dolly”,”pluginName”:”Hello Dolly”,”activateUrl”:”http:\/\/www.isanadventure.com\/wp-admin\/plugins.php?_wpnonce=0a78f22283&action=activate&plugin=hello-dolly\/hello.php”}}

installationfailed

At this point, I tried to just activate the plugin and I wound up with a blank page with the following errors

Warning: Cannot modify header information – headers already sent by (output started at /home/domain.com/domain.com/wp-content/themes/ThemeWP/functions.php:5) in /home/domain.com/domain.com/wp-includes/pluggable.php on line 1174

Warning: Cannot modify header information – headers already sent by (output started at /home/domain.com/domain.com/wp-content/themes/ThemeWP/functions.php:5) in /home/domain.com/domain.com/wp-includes/pluggable.php on line 1174

So after poking around at things for about an hour I found what appears to be the solution for most of the Installation Failed or Deletion Failed errors in WordPress with both themes and plugins.

I looked at the Child Theme I was using, which in my case had a single file (functions.php) and found that somehow I had added an extra line to it, which broke things.

<?php // Your php code goes here ?>

~

Note the space after the ?> and before the ~

I edited the file and deleted that line so it looks like

<?php // Your php code goes here ?>
~

And that was that! Everything worked fine after that including some issues I had with the dynamic search results on the plugins page which had been giving me nothing but a spinning circle every time I typed something in the search box. Hope that helps someone else.

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18 Comments

Leave your reply.
  • Nick
    · Reply

    November 18, 2016 at 9:48 AM

    Awesome!!! Fixed the problem, thanks 🙂 🙂 🙂

    • Joseph Turley
      · Reply

      Author
      November 18, 2016 at 10:57 AM

      Sweet! I’m glad this finally helped someone. 🙂

  • Kevin Boyle
    · Reply

    November 25, 2016 at 9:36 PM

    I’m having this exact problem but wondering where to head to to fix this code? Was it in the header, main index etc?

    Appreciate any help, thank you!

    • Joseph Turley
      · Reply

      Author
      November 25, 2016 at 10:38 PM

      Kevin,

      It is in the functions.php file inside your theme or child theme.

  • Avinash Kabra
    · Reply

    December 7, 2016 at 9:44 PM

    Thank you so much. You were very helpful.

    • Joseph Turley
      · Reply

      Author
      December 7, 2016 at 10:03 PM

      Happy to have helped!

  • Linda
    · Reply

    February 22, 2017 at 7:52 PM

    Thank you, thank you, thank you so much! This neatly solved my problem.

  • Vas
    · Reply

    September 16, 2017 at 8:06 AM

    So simple … thank you
    solved my problem as well

  • Girisimci Blog
    · Reply

    November 3, 2017 at 3:58 AM

    I have to thank for this post… Same as yours I had accedentally added an extra line at the end of my child themes funtions.php 🙁 You saved my day! Thanks

    • Joseph Turley
      · Reply

      Author
      November 3, 2017 at 4:06 AM

      Pleased to have been of service. 🙂

  • Adam
    · Reply

    February 22, 2018 at 6:46 AM

    In my case, it was because I accidentally allowed a 301 redirect to the wp-admin/ajax.php which redirected to the home page. That meant anything using the ajax file was being redirected!

  • Alan
    · Reply

    May 13, 2018 at 1:33 PM

    You are a beautiful human being. Thank you so much for sharing. x

  • JoelsBlog
    · Reply

    June 7, 2018 at 9:55 AM

    It didn’t work for me sir what else could be wrong here

  • Konrad
    · Reply

    June 30, 2018 at 5:07 AM

    Thanks for tip where to search 🙂
    In my case it was BOM signature in functions.php in child theme.

  • Devi
    · Reply

    September 20, 2018 at 8:56 PM

    Awesome! Simple and helpful solution.

  • asedap
    · Reply

    November 12, 2018 at 9:30 PM

    Just delete blank line on my functions.php and it works. I have no idea..how it works

  • Ganchor
    · Reply

    January 5, 2019 at 12:50 PM

    Great, just solved my 2 days problem, the wp site was showing blackscreen when refered from google search. found a huge chunk of codes in the functions.php. Thanks very much.

    • Joseph Turley
      · Reply

      Author
      January 5, 2019 at 12:59 PM

      Very happy to have been of service. 🙂

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