Common PDF Problems and How to Fix Them | PDFCrush

PDF too large, email rejected, formatting broken, job portal won't accept it, prints differently? Real causes and practical fixes for the most common PDF problems - no software needed.

PDF is supposed to be the format that works everywhere - same layout, same fonts, same appearance on any device. In practice, something goes wrong more often than it should. The file is too large to email. The job portal rejects it. The formatting looks completely different on someone else's screen. The print job comes out wrong.

Most of these problems have clear causes and straightforward fixes. This is a diagnostic guide: what is actually happening, and what to do about it.

Why Is My PDF So Large?

File size is the source of most PDF frustrations - emails bouncing, uploads failing, slow opens, mobile apps struggling. Before you can fix it, understanding why it happened makes the solution obvious.

Scanned pages

When you scan a physical document, each page is stored as a photograph. A single A4 page at 300 DPI in colour can be 3-6 MB by itself. Ten scanned pages becomes a 30-60 MB file, even though the actual readable content is just text on paper. The scanner captures every speck of dust and imperfection on the paper at full resolution - all of it stored in the PDF.

High-resolution embedded images

PDFs exported from PowerPoint, Word, or design tools often contain photos and diagrams at their original full resolution. One high-quality product photo can add 4-8 MB. A document with ten such images has a brutal total size before you've even considered anything else.

Print-quality export settings

Software like InDesign, Illustrator, Figma, and even PowerPoint defaults to print-quality export - 300 DPI or higher - because that is what commercial printers require. For a document you are only sharing digitally, 96-150 DPI is indistinguishable on screen.

Hidden overhead

PDFs carry things the reader never sees: editing history, document thumbnails, full copies of embedded fonts, layer data from the authoring tool. None of it is visible, but all of it adds file weight.

The fix

Compress the PDF. A good compressor re-encodes images at resolution appropriate for screen viewing, strips unnecessary metadata, and reduces the file to a fraction of its original size - typically without any visible quality change.

Scanned documents are the best compression candidates. A 20 MB scanned contract typically compresses to 2-4 MB. A 45 MB scanned property document can reach under 5 MB. The compression works because you are replacing oversized photographs of text with smaller photographs of text - and at normal reading size, 150 DPI looks identical to 300 DPI.

Why Does Email Reject My PDF Attachment?

You attach a PDF, hit send, and get an error. Or it looks like it sent but the recipient never receives it. Email attachment limits are almost always the cause.

If the email appears to send but never arrives, the recipient's mail server may be silently dropping it. Spam filters sometimes block large attachments even when the sender's server accepted them.

The fix

Compress the PDF before attaching. For most documents:

• A scanned invoice or contract starting at 12 MB typically compresses to 1.5-3 MB
• A presentation PDF starting at 18 MB typically compresses to 5-9 MB
• A text-only report starting at 4 MB typically compresses to 2-3 MB

If the file is legitimately huge - a multi-hundred-page document - compress first, then split it into sections and send as separate emails. Or upload to cloud storage and share a link instead.

If an email appeared to send but the recipient says they never got it, file size is the first thing to check - even if you think it was under the limit. Attachments close to the limit sometimes cause delivery issues due to email headers and encoding overhead.

Why Are Scanned PDFs So Much Larger Than Regular PDFs?

A two-page contract typed in Word might be 80 KB. The same contract scanned to PDF after signing might be 8 MB. A 100x size difference for identical readable content.

How regular PDFs store text

A text-based PDF stores words as mathematical instructions. The letter "A" is not a picture of the letter A - it is a set of vector coordinates describing how to draw it. This takes almost no space. A full page of dense text might be 5-15 KB. Scale it to any size; the text stays perfectly sharp.

How scanned PDFs store text

When you scan a document, the scanner photographs the paper. It does not recognise that those marks are letters - it captures everything it sees as a grid of pixels. A 300 DPI scan of an A4 page creates roughly 2480 × 3508 pixels - nearly 9 million pixels - for one page. Even with image compression, that is enormous compared to a few vector coordinates.

The scanner has no way to know which pixels are text and which are white space. It stores all of them equally. Which is why a 10-page scanned document weighs 10-30x more than the equivalent typed PDF.

The fix

For files you have already received: Compress the PDF. The compressor re-encodes page images at a lower resolution (sufficient for reading, not for commercial print) and dramatically reduces size.

For future scans: Scan at 150-200 DPI instead of 300 DPI for documents that will only be read digitally. The visual difference on screen is negligible, but the file is roughly half the size of a 300 DPI scan.

To make scanned text searchable: Run the document through OCR (optical character recognition). This adds a text layer to the PDF so you can search, copy, and select text - and it also helps with compression efficiency.

Why Does PDF Formatting Break on Another Device?

You open a PDF someone else created and the layout is completely different from what they described. Or you share a PDF and the recipient says it looks wrong.

Missing fonts

This is the most common cause. If the PDF does not embed the fonts used in the document, the viewer on the receiving device substitutes a similar font. Even a close substitute has different character widths. A line that fitted perfectly in Calibri might overflow by two characters when rendered in a similar-looking substitute - pushing text into the next line, shifting everything below it, breaking the entire layout.

The fix: re-export the PDF with fonts embedded. In Word, go to File → Options → Save → check "Embed fonts in the file". In Google Docs, exported PDFs embed fonts automatically. In design tools, look for the option in export settings.

Different PDF viewers

Not all viewers render documents identically. Adobe Reader, Chrome's built-in viewer, Preview on Mac, and Foxit all make slightly different interpretation choices when rendering complex PDFs - particularly for transparency effects, gradient blends, and overlapping objects. A design-heavy PDF might look perfect in Adobe Reader and slightly off in a browser viewer.

For important documents, test in both Chrome and Adobe Reader before sending.

Version incompatibility

Older PDF viewers sometimes struggle with newer PDF features - interactive elements, layers, and transparency effects created in modern tools may render incorrectly or not at all in outdated readers.

Exporting to PDF/A (the archival PDF standard) avoids most of these issues by restricting the document to features all compliant readers must support. Most export tools have a PDF/A option.

The fix for layout-sensitive documents

When exact layout matters - contracts, legal documents, formal reports:

1. Embed all fonts on export
2. Flatten any transparency before export
3. Test in both Chrome and Adobe Reader before sending
4. If the document uses unusual fonts, convert text to outlines in your design tool before exporting - this bakes letterforms as shapes so no font file is needed on the recipient's device

Why Did the Job Portal Reject My Resume PDF?

Job portals have become strict about what they accept. A rejection can mean several different things - size limit, wrong format, or a parsing failure that is invisible until you wonder why you are getting no responses.

Size limit exceeded

Most portals cap uploads at 2-5 MB. A well-formatted resume should be well under 1 MB. If yours is larger, it almost certainly contains embedded images (a profile photo, decorative elements) or was exported at print quality from a design tool.

Fix: compress the PDF, or strip decorative images from the template if they are not essential to the content.

Scanned resume - the ATS cannot read it

Many job portals feed resumes into ATS (applicant tracking systems) that extract text for parsing. If your resume is a scanned image or a photograph of a printed document, the ATS sees a picture - not text. It cannot read your name, your experience, or your skills. Your application may be silently dropped or filed under an empty record.

Fix: always submit a text-based PDF exported directly from Word, Google Docs, or a resume builder. Never submit a photo or scan of a printed resume for ATS-parsed applications.

Incorrect file type or PDF features

Some portals specify "PDF only" but reject PDFs containing interactive form fields, JavaScript, or embedded files. When in doubt, export to PDF/A-1b - a clean, universally compatible format - and try again.

Complex layouts confuse the ATS parser

Two-column resume templates, tables, text boxes, and graphic elements can cause ATS parsers to read text in the wrong order - across columns instead of down them - producing a garbled version of your experience. For ATS submission, single-column simple layouts parse most reliably.

Resume submission checklist

• [ ] File is under 1 MB (compress if not)
• [ ] PDF exported directly from Word or Google Docs (not scanned, not photographed)
• [ ] No complex multi-column layout or text boxes
• [ ] No JavaScript, interactive fields, or embedded attachments
• [ ] File name is clean: no special characters, no spaces (e.g., James-Rivera-Resume.pdf)

Why Does My PDF Open Slowly?

A PDF that takes five seconds to display the first page is usually suffering from one of two problems: it is large, or it is not linearised.

File size

A 50 MB PDF takes longer to transfer and render than a 2 MB PDF - especially noticeable on mobile, slower connections, and older devices. Compression is the first fix.

Not linearised (no fast web view)

Linearisation is a PDF optimisation that rearranges the file structure so the first page can display immediately while the rest of the document loads in the background. Sometimes called "fast web view" or "optimised for web."

Without linearisation, the PDF viewer must download the entire file before displaying anything. For a 10-page document, this means waiting for all 10 pages to arrive before seeing page one.

Most modern PDF export tools support linearisation - look for "optimise for web", "fast web view", or "linearise" in the export options. Enabling it makes a noticeable difference in perceived load time when sharing PDFs via email or web.

Too many pages without section splitting

Very long PDFs - 200+ pages - can be slow even when well-optimised. If you only need to share a section, split the PDF first and share only the relevant pages.

The fix

1. Compress to reduce total file size
2. Re-export with "optimise for web" or linearisation enabled
3. If only certain pages are needed, split and share those pages

Why Does My PDF Look Different When Printed?

The document looked correct on screen. The printout disagrees. Here are the most common causes.

Colour shift - screen colours vs print colours

Screens use RGB colour (red, green, blue light), which can display vivid colours that print cannot reproduce. Printers use CMYK ink (cyan, magenta, yellow, black). The conversion from RGB to CMYK causes colour shifts - particularly with bright blues, vivid greens, and saturated reds, which can appear duller, darker, or slightly different in hue when printed.

For everyday office documents, the auto-conversion most printers do is fine. For anything visual - marketing materials, brochures, design portfolios - export with a CMYK colour profile and test-print before finalising.

Font substitution changes layout

If fonts are not embedded in the PDF, the printer's rendering engine substitutes a different font - just as a PDF viewer would. The result is shifted spacing, overflowing text, and broken layout. Embed fonts on export to prevent this.

Print scaling settings

This is a very common source of confusion that is easy to miss. The print dialog has scaling options: "fit to page," "shrink to fit," "actual size." If "fit to page" is enabled when the document has narrow margins, the printer scales the content down to avoid cutting anything off. This adds white space around the edges and shifts the visual proportions of the entire document.

For documents where exact sizing matters - forms, contracts, anything with precise layout - always print at "actual size" (100%) and ensure the document margins account for the printer's non-printable area.

Non-printable margins

Home and office printers cannot print to the very edge of the paper. Most have a non-printable margin of 4-8mm around all sides. If your PDF has content right up to the edge - a full-bleed background colour, text near the margin - it will be cut off.

The fix: keep important content at least 5-8mm from the page edge, or use a printer that supports borderless printing (most photo printers do, most office printers do not).

Print checklist

• Print dialog: set to "actual size" or "100%", not "fit to page"
• Fonts are embedded in the PDF
• For colour-critical documents: export with CMYK profile
• Important content is at least 5-8mm from all page edges

Quick Fix Reference

A Note on Privacy When Fixing PDFs Online

When you fix a PDF using an online tool, your document goes to that tool's server. For a contract, medical record, payslip, or identity document, that is a real consideration.

PDFCrush processes all files locally in your browser using WebAssembly. Your PDF is never uploaded to any server. Compression, editing, splitting, merging - everything runs in your browser tab. Turn off your internet connection mid-process and it keeps working. There is nothing on a server to breach, retain, or misuse.

For sensitive documents, this is the right architecture to use.