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mysterious “Where is the debugger or host application running?” dialogue on non-debug swfs

Remember awhile back when you’d go to a flash site and randomly get accosted by a “Where is the debugger or host application running?” modal prompt? Haven’t seen one in a while have you? Happily these days debug swfs normally don’t pop open this dialogue unless you explicitly right click a debug swf and click on “Debugger” from its context menu. Unfortunely there are still some tricky situations where this prompt will still rear its ugly head.

My Google-foo (or Adobe?) has let me down on getting solid information on this but in my tests it appears this functionality changed with Flash Player Debugger 9,0,115,0 (Yeah, I thought it was earlier too). This is the debugger version that installs with Flex so even tho you may no longer get the prompt its keen to note that any viewer with a <9,0,115,0 Flash 9 debugger (like the 9,0,45,0 debugger that installs with Adobe CS3) will still receive it. In most cases this isn’t anything to worry about though as its second nature to turn off debugging on your production swf. However did you know you have to take into account all embedded and run-time loaded swfs as well?

After receiving reports of said infamous debugger on our production swfs and a lot of time spent investigating with Flash Switcher I found a couple insignificant embedded icon swfs and a few run-time loaded font swfs were the debug swf culprits. Duplicating the issue in the Flash 9.0.45.0 Debugger, what made matters worse is that each debug swf that loaded was getting its own modal popup and, atleast in Mac FF3, each consecutive modal popup was showing up blank but still needed to be clicked or the user was locked out of the site.

After another extensive google search the only thing I could find regarding this child swf debugger policy is a brief mention in Tinc Uro’s Blog regarding Flash Player 9 Update 3 (again Player 9,0,115,0). The one line from his release notes was: “210746 When a release swf loads a debug swf, flash player doesn’t look for the debugger”.  I’m assuming that this was the “fix” as this player version does indeed keep the issue from happening. So to prevent your viewers from ever getting spammed with “Where is the debugger” modal windows, ensure all your swfs (embedded and run-time loaded) are non-debug or force your viewers to update to the most recent flash player if they don’t have atleast 9,0,115,0.

With the proliferation of “dot” releases of the Flash Player its now really important to know which sub version of the player you are targeting. Looking at the Flash Player 9 version penetration rates at KickApps I was surprised to find around 80% of our audience had atleast 115. I’m not sure of the remaining 20% how many are debug players though.

Version        Penetration
9,0,124,0:    ~56%
9,0,115,0:    ~24%
9,0,47,0:     ~10%
9,0,28,0:      ~7%
9,0,45,0:      ~4%

Categories: actionscript, bugs Tags: , ,
  1. October 13th, 2008 at 00:24 | #1

    You must publish “release build” of your application. Detailed information is here: http://blog.vukuf.com/2008/10/where-is-debugger-or-host-application.html

  2. Gregg
    August 25th, 2009 at 07:59 | #2

    Do you work for Microsoft? Lots of information, but useless in solving the problem. I’m just a user, when I see something like this I am very suspicious and would like a proper fix.

  3. August 25th, 2009 at 08:05 | #3

    Hi Gregg. If you are a non flash developer getting this error when you visit sites you can just update your flash player (http://get.adobe.com/flashplayer/) to get rid of it

  1. October 15th, 2008 at 12:58 | #1