Fixing Corrupted Forms
How to handle XFA forms, broken AcroForms, and Apple Preview corruption.
The Apple Preview Bug
One of the most common causes of PDF form corruption is Apple's built-in Preview app on macOS. When a user fills a form in Preview and saves it, Preview often rewrites the AcroForm dictionary incorrectly, stripping appearance streams or misaligning the xref table.
If a Windows user opens that same file in Adobe Reader, the fields often appear blank. To fix this, the file must be either opened and re-saved in a compliant viewer, or flattened immediately after filling.
Technical Details
| Form Type | Architecture | Support Status |
|---|---|---|
| AcroForms | Standard PDF Dictionary | Widely supported |
| Static XFA | XML embedded in PDF | Supported mainly by Adobe |
| Dynamic XFA | Dynamic XML/JS | Rarely supported outside Adobe |
| Corrupted AcroForm | Broken Dictionary | Needs flattening or repair |
Next Step: Fixing Corrupted Forms (Next Article)
Common Mistakes
- Trying to fill XFA forms in a web browser (they will usually just display a 'Please wait...' message).
- Trusting Apple Preview for critical legal documents.
Cross-Reference & Links
- Fill & Flatten Tool
- Merge PDFs
- Split PDF
- Rotate Pages
- Remove Pages
- Extract Pages
- Metadata Inspector
- Edit Metadata
- List Form Fields
- Add Page Numbers
- Why Flatten PDFs?
- PDF Security Guide
- Browser Processing
- Fixing Corrupted Forms
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Frequently Asked Questions
Can your tool fix an already corrupted form?
If the data is still in the dictionary, flattening it might force the appearance streams to render. However, severe corruption is irreversible.
What is XFA?
XML Forms Architecture, an older, proprietary format created by Adobe, which is now deprecated in PDF 2.0.