Rows of small rectangles standing in for words — sometimes called “tofu” boxes, after their shape — mean one specific thing: your PDF viewer knows exactly which characters belong there, it just doesn’t have a font on hand capable of drawing them.
Why this happens
A PDF can either embed the font it uses — bundling the actual letterforms inside the file — or just name it and rely on the viewer to supply a matching font from the system it’s opened on. Embedding is the reliable option and most modern export tools do it by default. When a font isn’t embedded, and the viewing device doesn’t happen to have that exact font installed, the viewer has a character code with no matching glyph to draw — and a box is what every viewer falls back to for “I don’t have a symbol for this.”
This is most common with:
- Non-Latin scripts — Chinese, Japanese, Korean, Arabic, or Hindi text in a PDF built on a machine that had the right fonts, opened on one that doesn’t.
- Symbol and icon fonts — Wingdings, Webdings, or specialized mathematical/technical symbol fonts, which are rarely installed outside the software that ships them.
- Unusual or licensed brand fonts used in a document exported without embedding turned on.
How to tell it’s this, not something else
- Zooming in keeps the boxes crisp and uniform — they’re not blurry or pixelated, because the viewer is drawing a real (if wrong) shape, not failing to render detail. Compare with Why Is My PDF Blurry? if what you’re actually seeing is fuzziness rather than literal boxes.
- Only some words or sections are affected, typically ones that used a different font than the rest of the document, or the whole page if it’s entirely in a non-embedded font.
- Selecting the boxed text and copying it elsewhere sometimes reveals correct characters — proof the underlying text is fine and this is purely a display problem, not missing content.
Fixes, roughly in order of reliability
Ask for a version with fonts embedded, if the document came from someone else. This is the actual fix — everything else below is a workaround for when you can’t get that.
Open it on a different device, especially one more likely to have the relevant font installed — a Mac or PC with the right regional language pack, or the software that originally produced the file. If the boxes disappear, you’ve confirmed it’s a font-availability problem specific to your machine.
Convert it to Word, if you need to work with the actual text rather than just view it. PDF to Word reads the underlying character data — which is intact even when it can’t be displayed — and rebuilds it using Word’s own font handling, which often resolves the missing-glyph problem entirely since Word has broader system font access and better fallback behavior than many PDF viewers.
Run OCR if the text truly can’t be recovered as characters (rare, but possible with badly malformed font tables). OCR PDF reads the visual shape of whatever is rendering — even boxes, in the worst case — though this only works if the boxes are a rendering issue on top of real underlying glyphs, not if the original characters are genuinely gone.
Related, but different
This is not the same problem as text you can’t select or search at all — that’s usually a scan, not a font issue. See Why You Can’t Select or Search Text in a PDF if boxes aren’t what you’re seeing, but copy and search simply don’t work.
Ready? Try the free PDF to Word tool now to recover the underlying text — no sign-up, no watermark, and your file is never stored.