Huge Core Dump Files in WordPress Folders

What are core dump files, and what do they signify in WordPress folders? I was surprised to see my WordPress folder sizes increasing and FTP revealed huge ‘Core’ dump files in several folders of my WordPress installation. As they gobbled up my server storage space, I had no idea where these came from and what to do with them.

WordPress core dump files

I found this 38MB core file in the root directory of my WordPress installation

core file

As I looked in subfolders, I found another 46MB core file in wp-admin

core dump

As you can see these are large files and occupy huge storage space on our server. Thankfully my hosting by Dreamhost has unlimited storage space, so I need not worry; but if your hosting has limited storage, it could add to lot of extra charges. I downloaded and tried opening these core files with Wordpad and a mix of gibberish text and symbols appeared.

Core Dump Files

I looked around for possible solutions and found more WordPress bloggers reporting this issue in the WordPress forums. I learnt that these are called Core Dump files and Wikipedia says core dump records the working memory of a computer program usually when the program crashes. Core dumps are often used to diagnose or debug errors in computer programs.

In these forums some people advised we can delete these files and save space after backing up all files and database. Some advise the core files can be read using GDB, the GNU Project debugger. I am not sure if I should delete these files and maybe you can help.

I understand that these files are hosted on our server to keep a record of useful data when the site crashed on a particular day, but I wonder if any hosting engineer is debugging this data or diagnosing why the server or unstable processes crashed or terminated.

Check your WordPress installation and post a comment if you also have “Core” dump files eating your server storage space. What are you going to do about it?


  1. Carlos says:

    the only dump i know of is when i go to the bathroom.

  2. Jeffro says:

    @Carlos – I guess with a post like this, a comment like that is inevitable!

    @QuickOnlineTips – I maintain a WordPress enthusiast forum which contains quite a few smart people in the world of WordPress. I’ve since created a new thread asking them what these files are and what they do.

    I don’t have any core dump files on my install of WordPress. The only files that reach that size is my error_log which occassionaly I just delete and let it come back.

  3. Kevin says:

    Unless you plan on sending the coredump file to the wordpress/php people to figure out what the problem – or you feel comfortable digging though the debugger – it is perfectly safe to delete. You don’t even have to back anything up. Your host may be interested in the core files – but I doubt it. Most webhost techs wouldn’t be able to step through a debugger, and those that could would probably charge you for it.

    This doesn’t change the fact that something associated with your wordpress install (most likely PHP, but not necessarily) crashed and may do so again. If you aren’t already doing so you should be making backups, and keeping a copy off-site as it sounds like your host may be unstable.

    You might check and see what version of apache, mysql, php, etc… your host has installed and see if there are any known problems/bugs, specifically with wordpress.

  4. Ajay says:

    I don’t think anyone looks at it. But, you should clean these up at regular intervals, unless you have unlimited storage space

  5. Sumesh says:

    I have had core dump files on my design blog(see my author link) and was initially alarmed (whether it was the result of a hack or whatever).

    I asked the question on Twitter. A webdevs and a webhosting employee said that they’re caused by buffer being dumped(whatever that means) and advised me to disable plugins that hog resources.

    I’ve still not found an actual way to prevent it, or understand why it is appearing (I’m not interested in debugging).

  6. QuickOnlineTips says:

    Thanks for all your useful feedback. It seems something is buggy on the wordpress install that is generating these core dumps.

    Obviously no hosting engineer would be interested to look over the code in detail, unless necessary.

    Maybe some plugin is acting funny. I will try to find the problem.

  7. John Hoff - WpBlogHost says:

    Hello, been reading in my reader for awhile but this is my first time commenting.

    I think everyone pretty much has it down. It’s doubtful your host will be interested in these files, as well as you. Deleting them should be fine.

    However, if you’re at all a bit nervous, I’d say back everything up first. Always good to do.

    WordPress on it’s own shouldn’t be dumping a lot of files, I bet it’s a plugin like you suggest.

  8. Paul says:

    You may want to try pulling some plugins down after deleting the core file. My guess is you have a poorly written plugin that’s so hosed it causes the core dump(s) … it’s unlikely that WP itself causes those to happen.

  9. Twilight Fairy says:

    core dump files can be safely deleted, they are useful only if you want to debug what happened. Since WP is pretty much well tested before they release any version, it could be some plugin or some theme component causing the crash. you could send it to the WP guys anyway.

  10. Andy says:

    I’ve been getting masses of these ever since upgrading WP to the latest version. Could WP be to blame? My host is useless when enquiring, they write to bollock me for going over my disk quota and won’t offer any help or advice to resolve the issue. I’m going to start looking for a new host…

  11. Cash Advance says:

    I have noticed that these files show up on sites I use the newer version of XML sitemap generator plugin.

    Have not yet disabled the plugin for testing, but may soon.

  12. Pundit says:

    I believe that I have found the problem at least on my servers. It was PHP 5.2.10 there seems to be a bug in it that causes core dumps and other errors. I have recompiled to 5.2.9 and everything seems to be working just fine.

  13. Julian says:

    I would be 99% sure these core dump files were created by PHP. What caused the crash is the WP cron file, wp-cron.php.

    I am not sure exactly why wp-cron.php would cause the crash, but it may have something to do with pingbacks. A firewall on the server may be blocking them, causing a timeout (or perhaps in the absence of a timeout, the script runs infinitely until it crashes).

  14. Brian at says:

    We were setting up a website on Hostgator and after two or three days I noticed that there were hundreds (yes, hundreds!) of these core.xxxx dump files within the root folder and /wp-admin/. In total it was like 20GB of space used b/c each one was around 50MB each. Crazy!

    I got some help from Hostgator though (they’re amazing for cust. support) and it turns out that wp-cron.php was continuously looking for another file, the phpinfo.php file that is located within the root folder.

    They added the file there but the weird thing is that it was never there to begin with. I’m not sure if this file is created on a new WordPress install, but this was with WP 2.8.4.

    So, I’d recommend checking for this phpinfo.php file in the root folder.

    Thanks and good luck!

  15. Maggie says:

    I had about 20 of these core files in my /wp-admin/ directory, at about 40 MB each. This post saved my site. I couldn’t figure out what was happening to all my disk space, so thank God it’s something this simple.

  16. mediaverso says:

    we have found a solution for the core dump files after a long investigation.
    The solution is simple.
    Please, read the solution here: wordpress core dump files


  17. sankom says:

    I got some help from Hostgator though (they’re amazing for cust. support) and it turns out that wp-cron.php was continuously looking for another file, the phpinfo.php file that is located within the root folder.

  18. moliva says:

    I am not sure exactly why wp-cron.php would cause the crash, but it may have something to do with pingbacks. A firewall on the server may be blocking them, causing a timeout (or perhaps in the absence of a timeout, the script runs infinitely until it crashes).

  19. Cebu Tech says:

    i have lots of core files lately so i deleted the mall and gradually testing plugins which may cause it. disabling one plugin for a day and check if core is produced. and then a gain the next day…. you’ll discover it later.

  20. Kalpa says:

    Today for the first time I identified this file in my wp-admin folder too. 52 MB. IT is very annoying especially when making a backup. But I think it is just a file there with no harm.

  21. mobil sedan corolla says:

    does any body can solved this problem?. my site is dead :(

  22. Shannon at MajesticWarrior says:

    There are 3 main areas we found huge amounts of backup files on the server. The first is right after you access the Cpanel and click on File Manager. Backups can be stored here and I download them to my computer and remove them from File Manager. Also under File Manager –>public_html–>wp-content You can also find backups here as well and the 3rd area is roughly the same place File Manager –>public_html–>wp-snapshots. Sometimes you can also find backups underneath wp-snapshots. These files can take up a lot of room on the server. A good plugin to get to help with revision clean ups, Comments cleanup and Transients cleanup on the database which are stored on the server as well is, WP Rocket. Its an optimization plugin..

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