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Fonts are not embedded or are faulty

Every font that is used to display text must be embedded in the PDF, with all glyphs it uses, matching widths and a valid encoding. Most font findings go back to the program that created the PDF or to fonts whose licence forbids embedding; the reliable fix is to correct the font in the source and export again.

Updated

Messages you may see

  • PDF/UA-1 (ISO 14289-1) rule 7.21.4.1-1: The font program is not embedded
  • PDF/UA-1 (ISO 14289-1) rule 7.21.4.1-2: Not all glyphs referenced for rendering are present in the embedded font program
  • PDF/UA-1 (ISO 14289-1) rule 7.21.5-1: Glyph width … in the embedded font program is not consistent with the Widths entry of the font dictionary (value …)
  • PDF/UA-1 (ISO 14289-1) rule 7.21.6-2: A non-symbolic TrueType font encoding does not define a correct mapping to the Adobe Glyph List (…)
  • PDF/UA-1 (ISO 14289-1) rule 7.21.8-1: The document contains a reference to the .notdef glyph
  • PDF/UA-2 (ISO 14289-2) rule 8.4.5.5.1-1: The font program is not embedded

What the rule requires

ISO 14289-1 (PDF/UA-1) sets out the font requirements in clause 7.21; the Matterhorn Protocol 1.1 lists them under checkpoint 31 (Fonts). PDF/UA-2 has the same requirements in clause 8.4.5. The rule for Unicode mapping (7.21.7) has its own page: Character encoding failed.

Font requirements of PDF/UA-1 (clauses 7.21.3 to 7.21.8)
ClauseRequirement
7.21.3Composite (Type 0) fonts: consistent CIDSystemInfo, a CIDToGIDMap for embedded TrueType-based CID fonts, and embedded CMaps unless they are predefined ones.
7.21.4.1The font programs of all fonts used for rendering are embedded, and they contain every glyph that is used.
7.21.4.2If a subset font lists its glyphs (CharSet or CIDSet), the list is complete and correct.
7.21.5The glyph widths in the font dictionary match those in the embedded font program.
7.21.6TrueType fonts have encodings and cmap tables that allow every glyph to be found.
7.21.8No text refers to the .notdef glyph, the placeholder for missing characters.

Text in rendering mode 3 (invisible text, for example the text layer over a scanned image) is exempt from the embedding rules, because it is never drawn. The rules apply to every visible font, including common fonts such as Arial or Times; there is no exception for them.

Why it matters

If a font is not embedded, the PDF viewer uses a substitute. Lines can then become longer or shorter, words can overlap or run out of their boxes, and special characters can turn into boxes or wrong symbols. People who enlarge text, use reflow or change colours and fonts in their viewer are affected first.

A reference to .notdef means that a character could not be displayed at all. Sighted readers see an empty box or nothing, while the text layer may still contain the character. The visible page and the text that a screen reader announces then differ, which confuses people who use magnification and speech together.

Common causes

  • The font licence forbids embedding. Word then either substitutes the font or, with the option Bitmap text when fonts may not be embedded, converts the text into images.
  • A font used in the document was not installed on the computer that created the PDF.
  • A print-to-PDF driver or converter was set not to embed standard fonts.
  • Text was added or changed later in a PDF editor with a font that was not embedded.
  • Older Type 1 or symbol fonts with incomplete or unusual encodings were used.
  • Several PDFs were merged or optimised, and font subsets were combined incorrectly.

Example

A TrueType font without an embedded font program. The font descriptor has no /FontFile2 entry, so rule 7.21.4.1-1 fails:

8 0 obj
<< /Type /Font /Subtype /TrueType /BaseFont /Arial
   /FirstChar 32 /LastChar 122 /Widths 9 0 R
   /Encoding /WinAnsiEncoding /FontDescriptor 10 0 R >>
endobj

10 0 obj
<< /Type /FontDescriptor /FontName /Arial /Flags 32
   /FontBBox [-665 -325 2000 1006] /ItalicAngle 0
   /Ascent 905 /Descent -212 /CapHeight 716 /StemV 80 >>
endobj
Failing: Arial is only referenced, not embedded
8 0 obj
<< /Type /Font /Subtype /TrueType /BaseFont /KQXTRA+Arial
   /FirstChar 32 /LastChar 122 /Widths 9 0 R
   /Encoding /WinAnsiEncoding /FontDescriptor 10 0 R
   /ToUnicode 12 0 R >>
endobj

10 0 obj
<< /Type /FontDescriptor /FontName /KQXTRA+Arial /Flags 32
   /FontBBox [-665 -325 2000 1006] /ItalicAngle 0
   /Ascent 905 /Descent -212 /CapHeight 716 /StemV 80
   /FontFile2 11 0 R >>
endobj
Passing the machine check: embedded subset with /FontFile2

The prefix of six capital letters and a plus sign (KQXTRA+) marks a subset: only the glyphs used are embedded. Subsets are allowed. The /Widths array must match the widths in the embedded program (7.21.5).

How to fix it

Microsoft Word

  1. Use fonts whose licence allows embedding, for example the fonts supplied with Microsoft 365. If you are unsure about a purchased font, ask its vendor.
  2. Choose File > Save a Copy (or Save As), select PDF in the file type list, then More Options > Options.
  3. Keep Document structure tags for accessibility selected. Do not rely on Bitmap text when fonts may not be embedded: Microsoft describes that it uses bitmap images of the text, which screen readers cannot read.
  4. Save, then check the new PDF. In Acrobat or Reader, Document properties > Fonts shows which fonts are embedded.

If one font keeps failing, change it in the paragraph and character styles that use it, rather than in single passages.

Adobe InDesign

  1. Resolve missing fonts before you export; InDesign lists them when the document is opened.
  2. Replace fonts whose licence does not allow embedding. Prefer OpenType fonts.
  3. Choose File > Export > Adobe PDF (Print) or Adobe PDF (Interactive). On the Advanced tab of the print export, Subset fonts when percent of characters used is less than decides between subset and full embedding; both are fine for PDF/UA.
  4. Check the exported file.

Adobe Acrobat Pro

  1. Open Document properties (menu on Windows, File on macOS) and look at the Fonts tab. Fonts without "Embedded" or "Embedded Subset" are the ones to fix.
  2. Make sure the font is installed on your computer. Adobe advises this for encoding problems, and a font can only be embedded if Acrobat can find it.
  3. In Acrobat Pro, open Tools > Print Production > Preflight. Allyant describes the fixup Fix potential font problems among the PDF fixups of the profile library Acrobat Pro DC 2015 Profiles; according to Allyant it targets font encoding problems. Run Analyze and fix on a copy of the file.
  4. Check the result again. If the finding remains, change the font in the source document and create the PDF again.

Preflight changes the file. Keep the original, and check tags and reading order again after any fixup.

Check your PDF

Upload the fixed file to see which machine-checkable criteria it meets now. The report lists the remaining problems with their pages.

Open the checker

Questions

Do standard fonts like Helvetica or Times need to be embedded?
Yes. PDF/UA has no exception for the standard fonts of older PDF versions. Only invisible text in rendering mode 3 is exempt.
Is subset embedding enough?
Yes, as long as the subset contains every glyph that is used and, where present, the CharSet or CIDSet lists them correctly.
Can I convert the text to outlines instead?
Then there is no text left for screen readers, search or reflow. Outlined text has to be treated as an image with alternative text, which is a poor substitute for real text.

Sources

  1. ISO 14289-1:2014 – Document management applications – Electronic document file format enhancement for accessibility – Part 1: Use of ISO 32000-1 (PDF/UA-1) – International Organization for Standardization (ISO). Checked on 7 November 2026.
  2. ISO 14289-2:2024 – Document management applications – Electronic document file format enhancement for accessibility – Part 2: Use of ISO 32000-2 (PDF/UA-2) – International Organization for Standardization (ISO), 13 March 2024. Checked on 7 November 2026.
  3. The Matterhorn Protocol 1.1 – PDF Association. Checked on 7 November 2026.
  4. Save or convert to PDF or XPS in Office Desktop apps – Microsoft Support. Checked on 8 November 2026.
  5. Create and verify PDF accessibility (Acrobat Pro) – Adobe (helpx.adobe.com). Checked on 7 November 2026.
  6. How to Fix Font Issues with Acrobat's Preflight Tool – Allyant Support. Checked on 8 November 2026.
  7. Adobe PDF export options in InDesign – Adobe (helpx.adobe.com), 2 June 2026. Checked on 7 November 2026.