If you are a MathType user, chances are you’ve run across this error after some automatic “update” of your system (Windows updates always do it to me).

In the past I have always just reinstalled MathType and that fixes it, but that requries finding my copy of MathType and the registration code… I always thought to myself… there’s got to be an easier way! So, while on a break from working this morning (Sunday) at 5am, I thought… this is the morning to find the real solution to this problem! Here it is:

  1. Find your Fonts Control Panel (for me, that is in Start -> Control Panel -> Fonts).
  2. Find the MT Extra font and delete it. It will probably reappear. Delete it again. Repeat this deleting process until it is gone for good. (your system may have multiple copies of the bad file… one for every “update”)
  3. To make absolutely sure you have deleted every copy, close the Font Control Panel, and re-enter it. Check one more time to make sure that MT Extra no longer exists in your installed Fonts.
  4. In the Font Control Panel, go to “File” and then choose “Install New Font.” Now find your MathType program folder (for me that is c:Program FilesMathType) and then find MathTypeFonts. It will take a second for the computer to populate the folder with the available fonts, and you should see MT Extra in that list. Install the MT Extra font.

Why does this fix work? Apparently when the system “updates” it installs an older version of the MT Extra font (thank you Microsoft), with fewer characters, over the newer version of the font. This is why your system may have multiple copies of this font installed, and why it suddenly stops working.

You may have also seen strange character display issues, like when the multiplication dot on your computer looks like a little box on someone else’s computer. In this case, the 2nd computer is missing the correct MT Extra font.

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