WordPress Flash Uploader Fix for the HTTP Error

Learn Line Dancing in a Flash (by Ray Radlein)

Last week I mentioned that I was having problems with comment moderation since upgrading to WordPress 2.7. Well, I was also having trouble with the flash uploader. I would get an error and have to use the browser uploader. Not a big deal but it annoyed me and slowed me done because I could only upload one image at a time.

So, I also decided to tackle this when I did my WordPress spring cleaning and I found a solution that worked for me.


When I would try to use the flash uploader for images I would get an error that said HTTP Error in bright red and nothing would happen.

When I started doing some research on the WordPress forums I discovered that there were many causes of this problem and just as many possible solutions. My heart sank a little because I wanted one simple answer and didn’t want to try a lot of different solutions. I am, however, only going to discuss the solution that worked for me.

The error is often caused by mod_security, which is a security module installed by the web host. This can be corrected by modifying the .htaccess file and there are two ways to deal with this.

  1. Install the Image Upload HTTP Error Fix plugin. The plugin adds the necessary lines to the .htaccess file. I have not tried this plugin so can’t vouch for it but people seem to be using is successfully.
  2. Edit your .htaccess file. This file is at the root level of your WordPress installation. Download it via ftp, make a copy, and then add the following lines to it.

    #BEGIN Image Upload HTTP Error Fix
    <IfModule mod_security.c>
    <Files async-upload.php>
    SecFilterEngine Off
    SecFilterScanPOST Off
    #END Image Upload HTTP Error Fix

    Then upload the edited .htaccess back to the root level of your WordPress installation.

I used the second solution because I am familiar with editing the .htaccess file and didn’t want to install another plugin just to do this for me. If you are having a similar problem with the flash uploader this solution may correct it. This thread in the WordPress forums discusses other possible solutions if this one doesn’t work for you.

photo credit: Ray Radlein

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  1. says

    Plugin route may be easier for dummies though you never know the outcome of the plugin. I had some weird plugins in the past that updates robot.txt but I would back it up first, cross check it three four times before allowing the changes.

    Editing directly is a better approach like you and I would do (though I am not that good in .ht configurations). Backing up is a step that one should always remember :)

    Ajith Edassery´s last blog post – T3Leads review – An affiliate program that is exciting

  2. says

    Reading the code over, it makes total sense.

    For the unfamiliar, it’s overriding a server security setting. In other words, it’s not WP or Flash that’s the problem – it’s the server.

    Andrea_R´s last blog post – Two things

  3. says

    I would like credit for reading this, even though I am not sure exactly what was said.

    Although seriously, the more I just read these kinds of posts from you the more little bits of knowledge I am getting, so thanks so much! When I first started, I didn’t know what a php was! I still don’t precisely but I’m getting a vague idea. That’s progress!

    Tracy´s last blog post – 6 Things I secretly hope are included in life coaching

    • says

      Hi Tracy – I guess it would make more sense if you had ever had the error – so you’re lucky :-)

      If some of articles are difficult to follow you can also enjoy the photos at the top – I was especially happy with my find for today.

  4. says

    I need to get the anti-spam thing, about 95% of comments needing moderation are those. Jeez Louize, get a life people — no one needs your viagra and online slots already.

    LOVE the pic you chose for this.

    Jannie Funster´s last blog post – Potential Regalements

    • says

      Hi Jannie – Do you use Askimet? It’s not the only anti-spam plugin but it does work really well. And seriously, I think everyone who wants viagra has already purchased it. And the spammers are SO sexist – all their spam is targeted at men ;-)

      Thanks for mentioning the photo – I was really proud of that find.

  5. Sol says

    Hi –

    Thanks for your post. I have been using the flashuploader without any problem for a while. Suddenly it stops working and I cannot find the solution, despite trying many different “solutions”. ARGGHH!

    Now when I upload an image using the flashuploader, i just get the little red HTTP Error – and that’s it. And only in Firefox – IE works fine – curious eh?

    I also have another WordPress site, but there’s no problem with that one, so I figure “it must be something in this site”.

    So, I disabled all of my plugins – still no joy.
    Checked that Firefox was up to date – all good.
    Then I uploaded the .htaccess file – nope!
    Changed all of my setting back to default – nope.
    Contacted my webhost, gave them a username and password so they can recreate the problem and I’m hoping to get an answer back today….

    If that doesn’t work, I am facing the prospect of re-uploading my entire site and starting again…… if I decide I can’t live with the manual upload!

    Although It’s a not a biggie – it is sure annoying. WordPress is so great, but it does amaze me that these “erroneous” problems can come up that steal your time.

    I’ll keep you updated :-0

    • says

      Hi Sol – If nothing else has changed, it is most likely that something changed with your host.

      Did you update Firefox or add a new Firefox add-on?

  6. Sol says

    Hi Kim

    My host says they cannot replicate the issue. It must be Firefox playing silly devils with me…. but as I say, works fine with my other site!

    I’ve cleared my cache and cookies a half a dozen times, checked I’ve got the latest browser version (I do) and update Flash Player too…. still no luck!

    How maddening – and how curious…. Will post an update if I ever get to the bottom of it….

  7. Zudie says

    Just got my HTTP error resolved.
    Editing htaccess did not help, so I contacted my hoster. They whitelisted the WP/Flash upload so it would not trigger the mod_security rules anymore.

    Hope this helps someone else because I spent hours trying out differnet solutions.

  8. says

    Everything indicates that the error “HTTP Error” while uploading images is caused by a change in the Apache FastCGI module (mod_fcgid 2.3.6) that limits the value of the parameter MaxRequestLen to 128KB (very low). Previously this limit was 1GB.
    Therefore this problem is likely to occur only on servers running PHP in FastCGI mode and only when trying to upload a file larger than 128KB.

    The final and stable solution to this problem is well explained in the link that leaves our friend ntarantino.


    and it works perfectly! :)

    but that solution requires access and modify the configuration file of FastCGI. It can be done via SSH or asking the support team of your server to do so.

    An intermediate and fast solution I’ve found, for those who need to solve this problem right now and can not modify that file themselves, is as follows:
    – Install the plugin WPlupload (nice and efficient plugin that replaces the WP file upload form)
    – In the plugin settings indicate 128kb or less in the “Chunk size”
    – Enjoy :)

    Tell me if this solution works for you.


  9. Andrés says

    I found a bug in a Multimedia Library, in WordPress. It cannot accept filenames with an “x” between two numbers Ej: my-image-160×600.jpg

    If you replace the “x” or add a space like. my-image-160 x 600.jpg the file will upload fine.

    I hope this help someone.


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