On your Samsung smartphone, if you don’t like the default font, the device lets you choose from a few built-in alternatives. If those don’t suit your taste either, you can download additional fonts from the Galaxy Store. While a few fonts on the platform are free, most are paid. If you’d rather not spend money, you can use apps like zFont 3 from the Google Play Store to add custom fonts to the font selection menu in One UI. However, the brand does not officially allow unauthorized apps to add fonts to this section, and such apps have been relying on a loophole to make it work. Now, the company appears to have patched that loophole with One UI 8.5 and software updates bringing the March 2026 security patch. In other words, once you install One UI 8.5 or the March 2026 security update, you will not be able to add fonts from apps like zFont 3.Samsung Galaxy S25 users who installed the eighth beta version of One UI 8.5, as well as owners of other Galaxy smartphones who installed software updates offering the March 2026 security patch, have been reporting that they can no longer use fonts added through zFont 3 (via Piunika Web, Reddit, XDA Developers).More specifically, users who were previously using the default font are unable to switch to a font added through zFont 3 after installing the update. Similarly, users who had been using a font from zFont 3 but later switched to one of Samsung’s stock fonts or a font downloaded from the Galaxy Store are unable to switch back. After installing the updates, when selecting fonts added through zFont3, the phone displays the message, “This font is not supported. Contact the font provider. Uninstall this font?” and shows Cancel and Delete options.On Reddit, zFont 3 has confirmed that Samsung has patched the loophole that it was using to add fonts to One UI’s font selection section with One UI 8.5. Therefore, zFont 3 is not compatible with the new software.