The page count says fifty. The file size says forty megabytes. But page after page is just bright white nothing.
Content is in the file. Renderer can't draw it. Rebuild fixes it.
What's actually going wrong
Broken page stream. A specific instruction in the page's drawing commands is malformed, and the viewer skips the whole page rather than rendering partial content. Hidden content. White-on-white text or invisible overlays cover everything. Transparency error. The page uses an alpha-blending mode your viewer doesn't support.
In every case, the content exists but the viewer fails to put it on screen.
The quick fix
Compress the PDF in Flint. Even at light settings, the compressor rebuilds page streams from scratch. Broken instructions are replaced with clean equivalents, and content typically reappears.
If compression doesn't help, convert to JPG and back to PDF. This rasterises every page to flat images — whatever's visually present gets captured, hidden overlays and all.
If that didn't work
If pages are truly blank even after rasterisation, the content was never there to begin with. Get source and re-export.
For PDFs where only some pages render blank, split the PDF into individual pages, identify the broken ones, regenerate from source if possible, merge back.
Prevent it next time
Always test PDFs by opening them after creation. Use a different viewer to spot files that look fine in one place but break elsewhere. And keep source documents alongside PDFs for easy re-export.
FAQ
Why does my PDF look blank in one viewer but fine in another?
Different viewers handle modern PDF features differently. A viewer that can't render transparency or unusual fonts shows blank where others show content. Compress to flatten the structure.
Can compression always recover blank pages?
Often but not always. If the content is invisible because of overlay, compression strips it. If the content was never in the file, compression can't create it.
Does rasterising lose searchable text?
Yes — converting to JPG and back removes the text layer. Use OCR on the result to add searchability back: convert-pdf-to-word, then export back to PDF.
Why are my pages partly blank — some content, mostly empty?
Page stream has multiple drawing instructions; some succeed, some fail. Compression rebuilds the whole stream and usually recovers everything.
Blank pages with file content underneath need a rebuild. Compress in Flint and content reappears.