I have found an odd behavior of an uploading images into media library. Depends on a browser, I can select multiple files at the time or not. For example:

It doesn't work in Chrome and in Firefox:

Chrome and Firefox - Multiple select is not available

It works fine in Opera:

Opera - Multiple select is available

But it works fine in the Chrome browser on the machine of my colleague.

I thought that the reason is in Adobe Flash which isn't probably installed in my Chrome and is installed for Chrome of my colleague, but not, it isn't installed for both.

Maybe someone knows a reason of this behavior? I need to explain client why he can't select multiple files, but I don't have any idea and I can't recommend him to use Opera browser :).

  • yes is a adobe flash problem, to avoid this problem I remember you have to set Upload.Classic setting to true. Can you give a try ? Commented Jun 16, 2017 at 14:49
  • I guess if I set the Upload.Classic setting to true, the single file selection will always be shown. Or am I wrong? Commented Jun 16, 2017 at 14:51
  • @SitecoreClimber I tried and I was right. When I set true for Upload.Classic, I am always able to select just one file at the time. But on the contrary I need to have the opportunity to select several. Commented Jun 16, 2017 at 14:59
  • can you try on incogntito mode where you don't have extensions on your browser, do you have antivirus and your colleague not? Commented Jun 16, 2017 at 15:00
  • @SitecoreClimber We both don't have an antivirus. When I open sitecore in the incognito mode, the multiple file upload is available. Very strange. Commented Jun 16, 2017 at 15:04

3 Answers 3


I saw this behavior when you have a firewall, antivirus or cookies are corrupted. Somehow
Please try to delete all your cookies and try again.

Cookie with key : sc_fv contains Flash Version and probably somehow this one was corrupted.
On the method Sitecore.Shell.Framework.Commands.Media.MultiUpload.QueryState(CommandContext context) is verifying method UseFlashUpload

This method verify if your Sitecore Client SupportFlashUpload:

public virtual bool SupportsFlashUpload
        return this.GetFlashVersion().Major >= 9;

on the method GetFlashVersion it reads sc_fv cookie value:

    protected virtual Version GetFlashVersion()
    string cookieValue = WebUtil.GetCookieValue("sc_fv");
    if (string.IsNullOrEmpty(cookieValue))
        return new Version(0, 0, 0);
    string[] array = cookieValue.Split(new char[]
    if (array.Length != 3)
        Log.Error("Unexpected flash version cookie value: " + cookieValue, this);
        return new Version(0, 0, 0);
    int @int = MainUtil.GetInt(array[0], 0);
    int int2 = MainUtil.GetInt(array[1], 0);
    int int3 = MainUtil.GetInt(array[2], 0);
    return new Version(@int, int2, int3);
  • Thanks a lot for your answer and explanation! You really saved my time. Grate job! 👍 Commented Jun 16, 2017 at 15:50
  • Welcome, anytime. Commented Jun 16, 2017 at 15:51
  • Digging into how the uploader works (in 8.1 at least) it uses yui uploader which uses HTML5+XMLHttpRequest 2 or Flash as a fallback so if you don't have flash installed then it should work in most browsers: yuilibrary.com/yui/docs/uploader Commented Jul 26, 2017 at 14:01
  • oh friends.. there's opportunity here. HTML5 File API replaces flash as the uploader of choice. Flash does cover older browsers that won't handle HTML5 (which are few honestly). Hmm.. I guess I'd have to know telerik better to make good use myself Commented Nov 15, 2017 at 16:51
  • I manually updated the cookie value to 9.0.0 and it started working. Commented Jul 9, 2019 at 23:22

To add to this, Flash is indeed the culprit. If you're looking for something a little more perm. support recommends the following:

For the 'Upload File' dialog:

  1. Navigate to \Website\sitecore\shell\Applications\Media\Upload Media\
  2. Open the UploadMedia.xml file
  3. On line 27, add the attribute multiple="true" to the <input id="File" ... /> tag:
    <input id="File" name="File" type="file" style="width:100%" multiple="true"/>

For the "Upload files (advanced)" dialog:

  1. Navigate to the \Website\sitecore\shell\Applications\Media\UploadManager folder
  2. Open Upload.aspx
  3. Find the <input id="File0" name="File0" .../> tag inside the file and add the multiple="true" attribute:
    <input multiple="true" id="File0" name="File0" type="file" value="browse" onchange="javascript:return Sitecore.Upload.change(this)"/>
  4. Open the Upload.aspx.js file
  5. Search for ctl.type = "file"; line and put a new line after it:
    ctl.multiple = true;

Please note that this workaround has not passed full QA cycle. In case of any issue with upload please revert the changes.


The problem stems from the cookie sc_fv resetting to the value of 0.0.0 upon browser restart. The best workaround I found was using a browser extension such as edit this cookie to lock the value of the cookie to 31.0.0

Edit This Cookie sc_fv

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