I'm not sure what's changed, but all Windows updates are done, and all browsers are fully up to date. Chrome 40, Firefox 35, Opera 27.

This is what my fonts look like at the moment:

blurry fonts image

I have ClearType turned on, and if I open up Word and write some large type in the same font faces everything looks fine.

I tried changing the website I'm working on to Calibri, and that was still blocky and horrible even though it's a local font that I definitely have, and which Word displays correctly.

I've tried turning it off and on again. This is a recent problem (i.e., something has changed, it is not a problem associated with an initial installation).

  • 99% of those with font rendering problems all over their Windows O/S (like word in this case) only post about the appearance in their browser. It's now almost impossible to google for font rendering and find any page that doesn't revolve around browser font rendering technologies :(
    – ndemou
    Commented Feb 24, 2015 at 11:43
  • My initial posting did outline that fonts still looked fine in Word (for one) in the title of the question, but someone edited it to make it more generic. As a web dev though, yes, it was browsers that I mostly noticed the problem in.
    – Codemonkey
    Commented Feb 24, 2015 at 12:15
  • 1
    Sorry for the bitter comment Codemonkey. I came here after googling with poor results for maybe half an hour and was in a bad mood. BTW if the same fonts/sizes that appear ugly in a browser appear OK in Word then the accepted answer is not for you because it's about a system-wide font rendering bug which should affect all programs. It's easy to get confused with so many "moving parts" that play a part in this problem though. I surely did.
    – ndemou
    Commented Feb 25, 2015 at 7:45
  • This was 100.0% the problem with my system @ndemou. It wasn't system wide, but it was unquestionably KB3013455 that was the issue. Uninstalled it and the problem went away. Reinstalled it and it came back, applied MS hotfix for it and it went away. I didn't try Arial/Courier/Times in Word though, it was Montserrat and Calibri which maybe weren't affected. The hotfix definitely fixed my browsers etc though.
    – Codemonkey
    Commented Feb 25, 2015 at 10:40
  • 1
    I'm running into this issue in WIndows 10; the KB3013455 issue didn't fix it. Commented Oct 6, 2015 at 21:31

3 Answers 3


Let's try to build an answer with the full information here...

This is a known issue with Microsoft Update KB3013455, released on the 10th February 2015.

For a quick way to check if you have the update installed, open a DOS command prompt and type:

wmic qfe list brief /format:texttablewsys | find "KB3013455"

If this returns no text at all, the update is not installed; if it is installed, you'll see KB3013455 and more text printed out.

The issue can be resolved by either

  1. uninstalling the update (but this will leave you with a security vulnerability). A reboot will be required.

  2. Installing a subsequent update (the Microsoft official fix, released on the 18th Feb 2015):

    To resolve this issue, install update 3037639. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

    3037639 Fix for text quality degradation after security update 3013455 (MS15-010) is installed.

    This fix will take you to a page where it seems you're downloading the original KB3013455 all over again. Keep going, when you actually click to download you will get an option to get the fix, KB3037639.

    A reboot will be required.

    The fix was later included in Microsoft's automatic updates in March 2015.

Edit the list below to add affected systems:

  • Windows Vista SP2
  • Windows Server 2003 SP2
  • Windows Server 2008 SP2
  • Windows XP (for people on the Custom Support Program that keep receiving patches for XP)
  • Windows FLP
  • Windows Embedded (WEPOS, POS Ready 2009)

Edit the list below to add affected Fonts (only some font sizes show problems):

  • Arial
  • Courier New
  • Times New Roman
  • many others

Description of the problem (from here):

Essentially the small fonts (8-20pt) that normally result in a one-pixel line (think of lowercase "b" or "t" or "d") would now be a random mess between 1 and 2 pixels. Turning on "Clear Type" or font smoothing does "smooth" the garbage and it doesn't look as awful but that doesn't make the text any more readable.

  • 1
    Notice that I edited the answer to include the official fix from Microsoft, which is a new update.
    – pgr
    Commented Feb 20, 2015 at 12:03
  • After this fix my fonts are still a bit ugly (see dl.dropboxusercontent.com/u/242368/fonts.png) but not as ugly as after the patch that originally broke stuff (see i.sstatic.net/tVFUz.png where you can also see good-looking fonts before any of the patches). What's your results?
    – ndemou
    Commented Feb 24, 2015 at 11:34
  • I don't have such a good eye for Fonts, but I would say that for me the problem looks 100% solved. I can't see anything strange with my fonts after the fix... maybe you could check the other settings (Cleartype etc.) that you might have played with during the problem.
    – pgr
    Commented Feb 24, 2015 at 13:16
  • Thanks @pgr - if your schedule permits please share a screenshot of this rtf [dl.dropboxusercontent.com/u/242368/test.rtf] at 100% zoom. I haven't tweaked any other setting. Only thing that find worthy noting is that I only look at the screen of the affected servers remotely (RDP).
    – ndemou
    Commented Feb 25, 2015 at 7:57
  • Here you go: dl.dropboxusercontent.com/u/8232796/font_test.jpg Tell me if you see problems there.
    – pgr
    Commented Feb 25, 2015 at 12:50

Check the following link to fix it:


Author: vince31
go to start --> control panel --> security --> view installed updates search for or find KB3013455 installed on 2/11/15 highlight it, right click and select uninstall.

Your PC will need to restart and windows will configure the changes but all should be back to normal after that

  • 3
    While this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference.
    – Cfinley
    Commented Feb 11, 2015 at 15:59
  • 3
    @Codemonkey Cfinley is right in his comment as it is better to include the content of the link (or at least relevant parts of it) so the answer stays valid even if there is a problem with the link in the future.
    – laurent
    Commented Feb 11, 2015 at 17:41
  • This is irritating. I'm experiencing the same issue. Uninstalling the hotfix requires a reboot--which reinstalls the update. It's not listed in Automatic Updates so you can't add the update to the ignore list.
    – Nilpo
    Commented Feb 13, 2015 at 21:18
  • 6
    I am surprised nobody is worried about security. The flaw fixed by this update apparently allows any website to execute code on your machine just by embedding crafted TrueType font. Commented Feb 15, 2015 at 8:49
  • Do note, if you uninstall the update and nothing more, a next windows update will install the update again. Microsoft hasn't yet retracted the update. I uninstalled the update on a server of ours, rebooted it, and next day it was installed again.
    – LPChip
    Commented Feb 17, 2015 at 8:41

You can try this in Firefox and see if it helps...

Inside about:config, the gfx.font_rendering.cleartype_params.rendering_mode definitely changes the way the fonts are rendered on Firefox under Windows OS. You can make the changes and see live what the differences are. What you are going to want to do is actually search for this value and make sure it is the only one visible in your about:config window. The reason for this is below.

The options are as follows:

A word of caution. When making changes to this value on my system, choosing 1 completely removes all text rendered in the browser. This means all your tabs, interface, webpage and about:config text might become completely invisible. If this happens, don't freak out, just double click on the bar where the value should be and change it back to 0 or -1. This is why you want to do a search for the actual value first, so that there is only one entry visible and you can change it back if something goes wrong. Trust me, I learned the hard way.

Source: BugZilla

  • Thank you so very much. It occurred for me on FFv44.0.1 and the value of 2 worked for me. Commented Feb 11, 2016 at 17:11
  • "definitely changes the way the fonts are rendered on Windows OS": Does that mean that by changing that about:config option, it will change the rendering of fonts for one or more non-Firefox applications running on the Windows OS? I would hope not; I would hope instead that this affects only Firefox.
    – bgoodr
    Commented Oct 15, 2016 at 16:57
  • No it just meant Firefox for Windows OS. Sorry for the confusion. Updated answer to reflect.
    – CU3ED
    Commented Nov 5, 2016 at 3:14

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