You signed the PDF. Saved. The next open says 'this file is damaged'. The pre-signing version was fine; signing broke it.
What's actually going wrong
Signing tools rewrite the PDF structure to embed the signature. If the rewrite is interrupted, malformed, or incompatible with the source structure, the result is a broken file.
Common causes: signing software bug, original PDF had unusual structure the signer couldn't handle, save interrupted by sync or crash.
The quick fix
If you still have the unsigned original, redo the signing using a different tool. Sign PDF in Flint for a more robust signing process. The new signed copy should work.
If only the broken signed version remains, try opening in different viewers — some open files others refuse. If any viewer succeeds, use it to extract the content.
If that didn't work
Upload the broken file to Flint. The more aggressive parser sometimes recovers files other tools mark corrupt. Result lets you re-sign cleanly.
For critical signed documents lost to corruption, contact the signer for a fresh copy if applicable. Reproduction is faster than forensics.
Prevent it next time
Keep unsigned originals after signing. Use reliable signing tools. Don't sign over cloud sync while the file is uploading.
FAQ
Why does signing sometimes break PDFs?
Signing rewrites the file structure. Bugs in the signer or unusual source structures can produce malformed output. Rare but happens.
Can the signature be recovered if the PDF is broken?
Usually not separately. Either the whole file opens (and signature works) or it doesn't (and you've lost both content and signature). Try alternative viewers first.
Should I sign in a different tool next time?
If your current signer caused the issue, yes. Flint's sign tool is reliable across various source PDFs.
Will antivirus quarantine the signed file?
Sometimes — antivirus tools sometimes flag rewritten signed PDFs. Check quarantine if the file vanished after signing.
Sign again with Flint and bypass whatever broke the previous attempt.