Fix Garbled or Missing Text When Combining Large PDFs
Question details
The user experiences garbled, unreadable, or partially invisible text when merging multiple large PDF files originating from various architectural and engineering applications.
- Product
- Device & OS
- not provided
- Scenario
- Combining multiple large PDF files (e.g., 630 MB total) exported from external third-party software like AutoCAD, Revit, Bluebeam, and Microsoft Word.
- Observed behavior
- The text in the final merged PDF becomes garbled or invisible, even though the original source files display perfectly normal on their own.
Ensure you have backups of all original source PDF files before modifying them, and verify that your PDF editor is updated to the latest version to avoid known merging bugs.
Recreate Source PDFs with Fully Embedded Fonts
Prevent font conflicts during the merge process by ensuring all fonts are fully embedded when exporting the original files.
Garbled text usually occurs when two different source PDFs use the same subset font name but map to different characters. Embedding all fonts ensures the merged document doesn't mix up character maps.
Open the original document in its native application, such as AutoCAD, Revit, or Microsoft Word.
Navigate to the 'Export' or 'Print' menu and locate the advanced PDF settings or properties.
Check the option to 'Embed all fonts' or select 'PDF/A' compliance mode, which forces all fonts to be embedded into the file.
Save the new PDF files and attempt to combine them again.
Use Preflight Tools to Fix Font Encoding
Inspect and repair font problems in the existing PDFs before combining them if you cannot recreate the original files.
Rasterize Affected Pages
Convert problematic text-heavy pages into high-quality images to lock in the visual appearance before merging.
Combine PDFs Safely with WPS Office
WPS Office provides a robust PDF toolkit that handles font mapping intelligently. Easily merge large PDF files from different architectural and engineering sources while preserving text formatting and document integrity.
- 1. Open WPS Office: Launch WPS Office and navigate to the 'PDF' tab on the main interface.
- 2. Select Merge PDF: Click on 'Merge PDF' from the available PDF toolkit options.
- 3. Add source files: Add your architectural and engineering PDF files into the dialog box and arrange them in the desired order.
- 4. Merge documents: Click the 'Merge' button to generate the new, combined PDF without font corruption.
Frequently Asked Questions
Why does text turn into random symbols when combining PDFs?
This happens due to subset font encoding conflicts. If two source PDFs use the same subset font name but map to different characters, the merged file gets confused, resulting in random symbols or garbled text.
Can I fix garbled text in a PDF that is already combined?
Usually, no. Once the font encoding is scrambled during the merge process, it is difficult to reverse. It is best to fix the font embedding issues in the source files and recombine them.
Does file size affect PDF font corruption?
File size itself doesn't cause garbled text, but exceptionally large files often contain hundreds of embedded elements and fonts from various sources, increasing the statistical likelihood of a font conflict.
How can I identify which source PDF is causing the issue?
Try merging your files in smaller batches. Once you find a batch that produces garbled text, merge those specific files one by one until you isolate the document causing the font conflict.
