Silverlight 5 Error 1001 - Font Filename Issue - by MattJolly

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  Fixed<br /><br />
		This item has been fixed in the current or upcoming version of this product.<br /><br />
		A more detailed explanation for the resolution of this particular item may have been provided in the comments section.

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ID 719317 Comments
Status Closed Workarounds
Type Bug Repros 14
Opened 1/19/2012 2:05:38 AM
Access Restriction Public


I upgraded a user's machine to Silverlight 5 and immediately no silverlight apps (both ours and various "showcase" examples) would load. If you enable script debugging you get the 1001 error immediately - not even the blue dots indicating the xap being downloaded.

I tracked it down to a font with an ampersand (&) in the filename. As soon as I removed this font Silverlight worked again.

The user's PC was running Windows 7 Ultimate 64-Bit.
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Posted by ecooneyoo7 on 6/15/2012 at 2:10 PM
This article was a major help! Netflix error 1001 explanantion for windows problems, not so much.

I Think our issue is the same; 64bit win 7 os, have tried everything to get it to work, registry editing, installing/uninstalling
silverlight 5 countless times, rebooting over and over, reverting back to silverlight 4, using 7zip to go into the install exe and pull out the msi file and just running that - all to no avail. Need to mention IE, Firefox, Chrome browsers were broken previous to the fix, none would play netflix movie streams nor any other silverlight page. The 1001 error explanation I got from Netflix states that the fix only applies to Macs and is related to fonts. Fonts?? And what about windows machines?? Anyway, after a week of futility, I started to look for silverlight issues appied to win 7 and containing mention of fonts, and I found this articile;

There are a couple things mentioned here; problems can arise from 1) fonts with an ampersand in the name not preceded by a space and 2) an inordinate number of fonts installed. I check for both. When I went to Control Panel and opened up Fonts, it took forever to open, not a good sign. Finally it opened and it turns out I had 10,000 fonts installed!! A few years back I had installed a bunch from a bulk file and forgot about it. So I first deleted all of the fonts that did not have a designer name attached, you can sort by that column. Next I went and deleted any that had an ampersand preceded by a space in the name, I think there was one. Just for giggles, I then rebooted, uninstalled Silverlight 5, ran CCleaner on the registry, and made sure that "c:\Program Files\Microsoft Silverlight" and "c:\Program Files (x86)\Microsoft Silverlight" directories were gone.

I then went to netflix, tried to play a show, ran the install at the prompt for Silverlight 5 from the Netflix player page, right-clicked and opened up the Silverlight configuration panel and checked on the checkbox for DRM (you may not have to do this but it will prompt if needed). After refreshing the page, lo and behold, the show started to play and me = happy!! if your symptons and setup are similar to mine don't waste time trying the fixes from others, check the font issue first and see if it works.

Now all are fixed and running silverlight and playing netflix content flawlessly. I think the other way to reproduce it is to install 10,000 and see what happens.
Posted by Kirill Chilingarashvili on 5/3/2012 at 11:27 PM
I hope you fix it soon
MS have released new version which is broken in 2011,
a lot of customers are calling and complaining our app does not work, while it works and it is just newest version of SL is broken.
Once customers remove fonts with & in name plugin starts to work.
really nasty bug
I am glad I have found this link, without it I could not figure out what to do.

Also if I am not mistaken - I think they are pushing new version in updates so even customers having working 4th version will start to call soon.
Posted by kremisoski on 4/16/2012 at 9:54 PM
I agree with HasturFr. If this has been a KNOWN issue since January, then what in God's name is taking so long? I have already deleted 3 fonts, and Silverlight 5 is still not working and I don't have the option of reverting back to 4 because even IF Netflix happens to support 4 still, when I go to the downloads page to download Silverlight 4 by clicking on Microsoft's own damn links it still makes me install 5. This SHOULD have been phased out during beta testing, but apparently there either weren't enough beta testers to find this problem or Microsoft just DECIDED to ignore it and push a release build that would SCREW anyone who had a Netflix account or otherwise used Silverlight that just so happened to have fonts with ampersands in their names or any other conflicts ( as is the case with me since the fonts are gone ). In the case of Netflix, I should be blaming them in the first place for using this Silverlight garbage instead of Flash.
Posted by HasturFr on 4/3/2012 at 7:54 AM
We don't need a workaround, we need a patch !
Posted by incite on 3/20/2012 at 2:26 PM
We need a workaround, because one of our big customers can not delete the font gd&t markup because this is a font of the plm software from siemens. Thanks a lot.
Posted by Bryan200987 on 3/9/2012 at 6:46 AM
I had the same issue with a windows XP machine. Customer was using a web application based on silverlight and it upgraded to silverlight 5 and got the blank screen. Went into the fonts and found 2 fonts with the & in them and deleted them and fixed the issue. Thanks for posting the solution!
Posted by mixmike on 3/5/2012 at 6:01 AM
I did some testing:
1) An ampersand in the font filename does not matter.
2) An ampersand in the font name leads to a SL5 crash only if there is no space BEFORE the ampersand character.
    You can reproduce the error by renaming a font with a tool like Typograf.
Posted by PerfectShuffle on 3/3/2012 at 5:04 AM
Also just to confirm, it is an ampersand in the font name itself and not the filename that causes this problem.
Posted by PerfectShuffle on 3/3/2012 at 5:02 AM
I am also getting this issue. To reproduce just install a font with an ampersand in its name (for example, A&S Popcorn - and then try to load any silverlight app (either in or out of browser). You will see a blank rectangle where the application's controls should be displayed.

This only seems to happen with the SL5 developer runtime. The consumer runtime does not appear to have this issue.
Posted by Biggle10 on 3/1/2012 at 4:35 PM
Had same problem. There was an AT&T font. Once removed users were able to load SL5 apps.
Posted by mixmike on 3/1/2012 at 8:44 AM
Had the same problem: Some PCs of my customer had Silverlight 5 installed. My application didn't start anymore (RuntimeError 1001). After deleting the font "GD&T Markup Standard" the application is running again!

Thank you Matt!

I read a lot about other users that are having the same issue e.g. with the netflix site (seeing only a blank page).

@Microsoft development team: Please fix this error in SL5 it prevents a lot of users from seeing Silverlight content!

Posted by Travis S on 2/15/2012 at 6:43 PM
I have been searching for days for a fix to my Silverlight 5 issue. It would load a blank page in IE9, Firefox, and Chrome. All while on my other computer it loaded everything perfectly. The difference was one this particular system I had different fonts. In particular was a font with a "&" in the title. Once removed all the apps worked fine. I nearly gave up till I found this post after combing through so many others. Thanks Matt.
Posted by Microsoft on 2/8/2012 at 4:19 AM
Thanks for your update.

We are rerouting this issue to the appropriate group within the Visual Studio Product Team for triage and resolution. These specialized experts will follow-up with your issue.
Posted by MattJolly on 1/31/2012 at 4:41 AM

Sorry, it looks like I made a mistake in my diagnosis. The problem comes when you have a font installed which has an ampersand in its font name (not just the filename).

For instance, if you download and install this font you should see the problem I describe.
Posted by Microsoft on 1/31/2012 at 4:00 AM

Sorry for bothering. Is there any update?

It would be greatly appreciated if you could provide us with that information as quickly as possible.

Thank you!
Posted by MS-Moderator10 [Feedback Moderator] on 1/19/2012 at 6:37 PM
Thank you for submitting feedback on Visual Studio 2010 and .NET Framework. In order to fix the issue, we must first reproduce the issue in our labs. We are unable to reproduce the issue with the steps you provided. Could you please provide us with a dump file?

You can get detailed steps about how to get the dump file and call stack at

Or you can download a Visual Studio 2010 Diagnostic Tool from You can get detailed description about how to use it to collect dump file.

Please zip the file and use "FeedbackID-719317" as prefix of the file name.

You can use the following workspace to upload the file:
Password: 58oVCW*+@Q02Q

Thanks again for your efforts and we look forward to hearing from you.

Microsoft Visual Studio Connect Support Team
Posted by MS-Moderator01 on 1/19/2012 at 2:43 AM
Thank you for your feedback, we are currently reviewing the issue you have submitted. If this issue is urgent, please contact support directly(