Custom font makes the Android app fail to load a book and then crash

I added a custom font in the Android app on an e-ink Android tablet. After selecting it, books won't open and the app crashes shortly afterwards. Built-in fonts are fine.

Resolution: This is the long-standing Android bug with spaces in custom font file names -- the font path is not handled correctly, so opening a book with that font selected throws and takes the app down. Rename the font file so it contains no spaces (MyFont-Regular.ttf rather than My Font Regular.ttf) and re-add it in the app, then reselect it. If the app is already stuck, clear the custom font selection first and confirm a book opens with a built-in font before adding the renamed file back.