This page is part of The Ultimate Font Guide, an introductory font manual that explains the basics of fonts and how to install fonts, use them in different applications and more.


If you have a Macbook, you might have bumped into this pop-up while installing fonts.

Font Book’s font validation system is telling you that ‘Problem may have been found with some fonts during validation’ and is asking you to review/validate the font.

It might look like a scary warning, but in fact, this error should not stop you from enjoying the font on your Mac/iOS. In this article we will tell you why!

Strict font validation

The Mac/iOS has very strict font validation and can fail for many reasons. This does not mean that you cannot install the font on your Mac. In almost all cases, the font will work perfectly fine!

In this article we will explain why you get this error and how to resolve it, so you can install your new fonts with ease.

Serious error or warning messages

This pop-up appears due to a technical issue with the font validation. Mac does a lot of checks when installing a font and when it finds something is not how it wants it to be, it will show this message.

There are 2 types of errors that can appear:

  1. Serious error and you cannot use the font
  2. A warning notification that minor problems were found

The short answer why this happens

A font is built up by coordinates and the font validation fails because the font is programmed with too many coordinates. The font, however, works fine. This triggered warning cannot be solved without re-creating the font and reducing the coordinates (which would result in a totally different font).

But the font can be installed as it is and be used on your Mac without any issues! Simply tick ‘Select all fonts’ and click ‘Install Checked’ and your installation will be completed.

The long answer why this happens

If you think it is interesting to learn in more detail how this works, just keep on reading!

Each font is constructed of a path of coordinates. These coordinates tell software such as Photoshop how the font should be drawn.

For most fonts, like the Verdana font, the coordinates will look like this:

Each blue dot is a coordinate. This is easy for the system to draw and it is very easy to validate for Font Book.

Decorative fonts have way more coordinates, which makes them heavier to use but also allows for different curves & flows. We will show you this works using the Motherline Blocks font as an example.

If you would open up this font, you will see that it has a lot of coordinates:

Every blue and red dot is a coordinate. So where Verdana has 13 coordinates to draw the W, Motherline has over 1100.

This is because the Motherline font is extremely detailed, if you look up close:

Every outline that is not fluid and every white spot inside the glyph has to be drawn. This is what gives the block version of the Motherline font its characteristics.

For Font Book these detailed coordinates are just too much and as a result of that, it will throw out the error.

If you would install this font in Windows, it would have the same problem (that it’s too much to draw). The difference is that Windows will not give an error, it will just revert to a default font (see image below). However, these more detailed coordinated fonts will install and work just fine on both Mac and Windows!

On slower computers it might take a bit more time to render the font, because also the application you use has to go through all the coordinates. This shouldn’t stop you from using it!

How to remove the error message while installing?

The only ‘fix’ for removing this error message would be to reduce the number of coordinates, which would basically result in a different font. The easiest thing to do is to simply ignore these errors when they appear and install the font.

We hope that you will keep on enjoying your fonts on your Mac/iOS!

If you have any further questions or need any help, you can contact us at [email protected]