The PDF opens fine but tools are greyed out. Edit, copy, print — all unavailable. The file says 'requires permission password to change'.
What's actually going wrong
PDFs can have two passwords: user (to open) and owner (to change permissions). What you're hitting is owner-password protection — the file opens for viewing but restricts editing, copying, printing, or some combination.
The owner password is required to lift these restrictions.
The quick fix
If you have the owner password, upload to Flint's unlock PDF. Enter the owner password. Flint produces a copy without restrictions.
For PDFs that legitimately belong to you (you created them), you should have the owner password. Check password manager or wherever you stored it.
If that didn't work
If you don't have the owner password and the file isn't yours, you can't legitimately remove the restrictions. Contact the file owner for an unrestricted version.
For restrictions that block specific use cases (printing for personal use, copying for legitimate research), reach out to the file owner. Most respond to reasonable requests.
Prevent it next time
Only apply permission restrictions when they serve a real purpose. Store the owner password securely. And consider whether restrictions actually prevent the abuse you fear, or just inconvenience legitimate users.
FAQ
What's the difference between user and owner passwords?
User password is needed to open the file. Owner password is needed to change permissions. PDFs can have one, both, or neither.
Can I bypass permission passwords?
Only with the owner password. Modern PDF permission encryption can't be cracked for arbitrary files. Get the password from the owner.
Why do some viewers ignore permissions?
Permissions are honoured by compliant viewers. Some viewers (Flint and others) honour them when displaying but offer unlock paths for users who have the owner password.
Are permissions secure against determined attackers?
User passwords with strong encryption are very secure. Owner-only passwords (without user encryption) provide only viewer-honoured restrictions, not cryptographic enforcement — easier to bypass.
Got the owner password? Unlock in Flint. Don't? Contact the owner.