One UI March 2026 update breaks custom fonts on Galaxy phones

The March 2026 security patch for One UI 8.5 is now available, and multiple Samsung Galaxy phones have started to receive it. However, per early reports, this update breaks custom font support, and the issue appears to be affecting multiple users.

Per the user reports, after updating the phone, it's not possible to switch to a different custom font. As some users note, when attempting to switch from one custom font to another, the phone fails to roll back to the previous one. In such cases, the users are forced to use the default fonts.

zFont 3, a font and emoji changer app, has officially announced that the app has lost support on One UI 8.5, and noted that the update has patched a flaw that allowed bypass of font restrictions. Moreover, a thread on XDA Forums mentions that Samsung has added a new feature in the latest update that checks certificate validity.

Specifically, this change checks the SHA-256 hash of a font, and only the APKs signed by Monotype, the contracted font vendor of Samsung, pass. Samsung's own platform keys also get the okay sign, but the others don't. A member from the XDA thread notes that 18 different bypass methods were tested on an updated Galaxy S26 Ultra (get a $200 gift card for free when ordered from Amazon), and all of them failed.

So, as of now, Galaxy phones with the March 2026 update can only apply fonts from first-party sources. However, users with a rooted phone that's running LSPosed can still install third-party fonts through MonoPatcher.