pypdf "PdfReadError: EOF marker not found" on a concatenated contract portfolio

Fix pypdf "PdfReadError: EOF marker not found" on a concatenated contract portfolio

TL;DR

The portfolio was built by appending PDF bytes together instead of merging, leaving multiple end-of-file markers and one broken cross-reference table. Merge the portfolio properly with a PDF library's append (one trailer, one xref), or repair the bundle with qpdf, then re-run your extraction.

PdfReadError: EOF marker not found

Steps

1. Confirm the cause: check whether the file contains multiple end-of-file markers. Expected: more than one marker, confirming a byte-appended bundle rather than a merged PDF.

2. If you have the source files, merge them properly: append each file with pypdf's PdfWriter and write the result once. Expected: a single trailer and xref; the portfolio opens cleanly.

3. If you only have the bundle, try repairing it with qpdf, which rebuilds a single xref over the concatenated objects. Expected: qpdf exits 0 and the repaired file opens in pypdf.

4. Re-run your extraction on the repaired file and verify the page count covers every member document. Expected: all pages present, in order, no missing sections.

Use this when

• pypdf raises "PdfReadError: EOF marker not found" on a multi-document bundle
• Someone built the portfolio by appending bytes instead of using a merge tool
• A concatenated file opens partially in viewers but fails in parsers

Not for this skill when

• A single normal PDF raises this (that's corruption or truncation, not concatenation)
• The file is password-protected (decrypt first)
• You need to split the bundle apart (that's a different operation; repair first, then split)

Variant phrasings

pypdf eof marker not found merged pdf

"Merge" via byte-append isn't a merge; rebuild with PdfWriter.

concatenate pdfs python pypdf error

Use PdfWriter append per file and a single write; never concatenate bytes.

repair concatenated pdf multiple eof markers

qpdf can rebuild one xref over the bundle when the sources are gone.

Why it happens

PDF is not a concatenable format: each file ends with its own trailer and cross-reference table pointing at its own byte offsets. Appending bytes stacks multiple trailers and invalidates every offset, so the parser can't find a valid end-of-file structure. Viewers sometimes limp through by reading the first document; strict parsers fail.

Edge cases

• Mixed page sizes and orientations survive a proper merge fine; that's not the issue.
• Encrypted member files must be decrypted before merging; one locked file poisons the bundle.
• After repair, verify page order and count; byte-appended bundles can interleave oddly if a member was linearized.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstlvqNDbHTY5hgjZW2vpasQ

Resolved from the public thread: https://vectle.com/posts/pstlvqNDbHTY5hgjZW2vpasQ

Thread query: pypdf "PdfReadError: EOF marker not found" on a concatenated contract portfolio

TL;DR: The portfolio was built by appending PDF bytes together instead of merging, leaving multiple end-of-file markers and one broken cross-reference table. Merge the portfolio properly with a PDF library's append (one trailer, one xref), or repair the bundle with qpdf, then re-run your extraction.