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Chinese characters rendered as empty squares, hashes, or other replacement marks in a PDF are a symptom, not a diagnosis. The export may have embedded a font without the required Chinese glyphs, used a different font fallback, or produced a file whose visible appearance is fine but whose extracted Unicode text is wrong. Product issue records document all of these possibilities. To identify the cause in your file, compare export paths and viewers, check font coverage, test both visual rendering and text extraction, and record the exact application, version, operating system, source font, and export route.
Why do Chinese characters become boxes in a PDF?
A PDF renderer can draw a character only when the PDF’s resources provide a glyph for it. If the selected or embedded font lacks that glyph and the exporter does not find a suitable fallback, the viewer may display a tofu box, a hash, or another replacement mark. DevExpress Support attributed one reported CJK export problem to report fonts that lacked the corresponding glyphs and directed users to later documentation about PDF font fallback.
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That explanation concerns a particular product and file. It does not prove that every PDF showing boxes has an encoding defect. The source text can be perfectly valid Unicode while the export fails at font selection or embedding. Conversely, a PDF can look acceptable while its text layer contains incorrect code points. Treat the visible box as evidence that something in the rendering chain failed, then test which layer failed.
What are the main failure modes to distinguish?
These cases look similar to a reader but require different remedies. Use the symptom and the integrity check together rather than labeling every problem “encoding.”
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| Failure mode | What you may see | What a check can reveal | Documented example |
|---|---|---|---|
| Missing glyph or unsuccessful font fallback | Boxes, hashes, or missing Chinese characters | The selected or embedded font does not contain the requested glyph | DevExpress Support described a report-font glyph-coverage problem; an Atlassian ProForma record describes CJK output with missing glyphs when no CJK font was bundled. |
| Export-path-specific failure | One PDF export route shows boxes or garbling while another route looks correct | The source page and text may be unchanged; the exporter, not the document, is the differentiator | A Plane issue report says its built-in PDF export failed for Chinese while browser print-to-PDF rendered the same page correctly. |
| Wrong regional glyph form | Characters are present but their shapes look Chinese-style instead of the expected Japanese forms, or otherwise look regionally wrong | Text remains selectable and semantically present; the problem is glyph design or font selection, not absence | An Atlassian record reports Japanese Kanji rendered in Chinese-style forms. |
| Text-extraction mapping error | The page looks readable, but copied or extracted characters differ from the source | Extraction returns a different Unicode code point even though a shared glyph was drawn | Apache PDFBox documents CJK extraction cases in which different Unicode characters can map to one glyph and extraction can return a different code point. |
These categories can overlap. A file might have missing glyphs in one paragraph, regionally inappropriate forms in another, and an extraction problem that is invisible on screen. Diagnose each symptom separately.
How can I tell whether the problem is the font rather than encoding?
Start with the font configured in the source application and the fonts actually embedded in the PDF, if the application exposes that information. Confirm that the chosen typeface covers the specific Chinese characters in the document, not merely that it is advertised as a “CJK” or multilingual font. A fallback chain can also matter: a font may cover common Han characters but miss a less frequent character, extension block, or punctuation mark.
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- Copy a problem character from the source and verify that it is the intended character, not a replacement symbol already present before export.
- Note the exact font family, weight, style, and any per-character formatting. A bold or italic face can have different coverage from the regular face.
- Look for application settings named font fallback, substitute fonts, CJK support, or font embedding. The wording differs by product.
Check the exported PDF
- Open the PDF’s document or font properties in a viewer that lists embedded fonts. Record the family and whether it is embedded or subsetted.
- Compare a page containing common Chinese characters with one containing the characters that fail. Selective failure points toward coverage or fallback rather than a blanket encoding problem.
- If the exporter offers a “PDF/A,” “embed fonts,” or similar option, record whether it was enabled. Do not assume that a setting with “embed” in its name guarantees complete CJK coverage; verify the resulting file.
The DevExpress case is useful because it identifies the missing-glyph mechanism, but it is not a universal prescription to install one particular font. The correct font depends on your source language, licensing, operating system, and the exporter’s fallback behavior.
Why should I compare different PDF export routes?
Export implementations do not all use the same rendering engine or font pipeline. A built-in exporter may construct PDF text objects and embed fonts differently from a browser’s print service. In the Plane issue report, Chinese appeared as squares or garbled through the built-in export while printing the same page to PDF in a browser produced correct text. That is evidence that the failure followed one path in that product, not proof that browser printing is a general fix.
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- Export the same source document using the normal PDF command.
- If the application has another route, such as print-to-PDF or a web print view, create a second PDF without changing the source text.
- Open both files in the same viewer and compare the exact characters and pages.
- Open both files in a second viewer. If only one file fails, preserve both files for support; the contrast is diagnostic evidence.
A path-specific difference narrows the search to the exporter, its font handling, or the options passed to it. It does not establish that the source text is correctly encoded, because the two routes may also produce different text layers.
How do visual rendering and text extraction differ?
They are separate tests. A viewer can draw a glyph correctly while the PDF’s internal character mapping causes copy-and-paste or search to return the wrong character. The reverse can also occur: the text layer can contain the intended Unicode while the viewer cannot draw it because the embedded font lacks a glyph.
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- Inspect the PDF in at least two viewers at a high zoom level.
- Check whether boxes occur only in one viewer, only on one operating system, or in every viewer.
- Compare the shape of the character with a trusted source when the issue is a regional form rather than an empty box.
Text-integrity test
- Select a problem character and paste it into a plain-text editor or Unicode-aware field.
- Use the viewer’s search function for the source character and for the character obtained by copying. Record which one succeeds.
- If you use a command-line or library extractor, compare its output character-for-character with the source. PDFBox’s issue record shows why a visually correct page can still produce a different code point when multiple Unicode characters share a glyph.
Do not call a file “fixed” merely because the boxes disappeared. A replacement font or rasterized page may improve appearance while removing selectable, searchable text. Record visual and extraction results independently.
Could the characters be present but rendered in the wrong regional style?
Yes. CJK fonts can choose different glyph designs for the same or related Han characters. An Atlassian record describes Japanese Kanji displayed in Chinese-style forms even though the characters were present. This is a glyph-shape or font-selection problem, not the same as a missing-glyph box.
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To investigate, compare the extracted character with the source and inspect the font family used for the affected run. If selection and search work but the form looks wrong, focus on a font whose regional design matches the document and on the application’s language or locale settings. Do not replace characters in the source simply because their outlines look unfamiliar; that can damage the text while leaving the underlying issue unresolved.
How much do application version, operating system, and locale matter?
They can change both the user-interface fallback and the PDF export behavior. Issue records for PDFCraft describe a released Windows build that still lacked a Chinese UI fallback change merged afterward, while another report separates PDF page rendering from UI rendering and records operating-system- and locale-specific fallback behavior. These examples concern that application’s UI and versions; they demonstrate why a report without environment details is hard to reproduce.
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- Application name and exact version or build number.
- Operating system and, where relevant, display language and regional settings.
- Source font family, style, and any fallback or substitution settings.
- Export command, print path, PDF standard option, and whether fonts were supposed to be embedded.
- PDF viewer name and version, plus the result in a second viewer.
- A small source file that reproduces the problem and the resulting PDF, if sharing is permitted.
Version information is not administrative trivia. The Atlassian records identify affected and fixed product versions, so two users can see different outcomes from the same source document after an upgrade or configuration change.
What is a reliable troubleshooting sequence?
Follow the sequence below so each test changes one variable at a time. It produces evidence you can use with the application vendor instead of a guess about “encoding.”
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- Verify the source characters. Select the Chinese text in the original document and paste it into a Unicode-aware editor. If it is already wrong there, repair the source before testing PDF export.
- Make a minimal sample. Create a short file containing several characters that fail, several that work, and any punctuation or rare characters involved. Keep the font and formatting explicit.
- Repeat the normal export. Save a fresh PDF and note the exact command, options, application build, operating system, and time of export.
- Test another viewer. Open the same PDF elsewhere. A difference between viewers is evidence about rendering or font interpretation, not automatic proof that either viewer is correct.
- Test another export path. Use the application’s alternate print or export route, when available, without changing the sample. Compare the pages and text layers.
- Inspect font resources. Check which fonts are embedded or substituted and whether the configured font covers every failing character. If the application has a fallback list, record its order.
- Test selection and extraction. Copy the visible characters, search for them, and compare extracted text with the source. Keep a separate note for visual failure and Unicode mismatch.
- Reproduce on a second environment if possible. A different operating system, locale, or application build can show whether the behavior is environment-specific. Preserve the original failing file for comparison.
When does a different export path help, and when does it hide the problem?
A second path helps when it isolates a defective exporter or fallback implementation, as the Plane report illustrates. It can hide the problem if it rasterizes pages, substitutes a different font without preserving text mappings, or otherwise changes the document rather than correcting the original PDF pipeline.
After any workaround, test three properties separately: the glyph shape, copy-and-paste fidelity, and searchability. Keep the workaround qualified as product-specific unless you have reproduced it across the same application and version that generated your file.
What should I tell application support?
Send a concise reproduction package rather than a screenshot alone. Include the minimal source file, the failing PDF, a PDF from any alternate route, and screenshots showing the same page in two viewers when available. State which characters fail, whether they are boxes or wrong forms, and whether copying returns the intended Unicode.
List the application build, operating system, locale, source font, export command, font-embedding options, and viewer versions. This level of detail lets support distinguish a missing glyph from a path-specific exporter defect, a regional glyph-form choice, or an extraction mapping problem. Avoid claiming an encoding bug until those tests identify an incorrect text mapping.
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What can this evidence establish—and what can it not?
The cited support and issue records establish that multiple CJK PDF failure modes occur in real products: missing glyphs, export-path differences, regional glyph forms, and extraction mismatches. They do not provide a prevalence rate, a universal font recommendation, or a diagnosis for an unidentified PDF. Each record is tied to a product, version, platform, and reproduction context.
For your file, the strongest conclusion comes from converging tests: font coverage explains boxes across viewers; an export-path comparison identifies where the behavior enters; visual-versus-extraction checks separate rendering from text integrity; and version and platform data determine whether a known product defect is plausible. Until those facts are recorded, “encoding bug” is only one hypothesis among several.
Frequently Asked Questions
Can a PDF viewer alone cause Chinese boxes?
It can contribute if viewers interpret embedded fonts or fallback resources differently. Open the same file in another viewer and compare it with a second export; a viewer-only difference is useful evidence, but it does not identify which interpretation is correct without checking the font resources and text layer.
Will embedding every font guarantee correct Chinese text?
No. Embedding a font helps only when that font contains the required glyphs and the exporter maps characters to it correctly. A file can still have regional glyph-form differences or an incorrect extraction map after fonts are embedded.
Why does copy-and-paste produce the wrong Chinese character when the page looks fine?
The visible glyph and the PDF’s Unicode mapping are separate. PDFBox has documented cases where different Unicode characters share a glyph and extraction returns a code point different from the input, so a readable page does not prove text-layer fidelity.
What is the most useful evidence for a vendor bug report?
Provide a minimal source sample, the failing PDF, and a PDF made through any alternate route, along with exact application and build, operating system and locale, fonts, export settings, viewer results, and copy-and-paste output. Identify the specific characters and whether the failure is visual, extraction-related, or both.
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