You enter the password to open the PDF. You make a change. You save it. Open it later — and it asks for the password again. Or your viewer doesn't have a 'remove password' option at all.
Password removal is a specific operation that not every tool exposes.
What's actually going wrong
Entering a password to open a PDF doesn't remove the password. The file is still encrypted; you're just decrypting per-session. To permanently remove the password, you need to save a new copy without encryption — and many viewers don't offer that.
There are also two kinds of passwords: user (required to open) and owner (required to change permissions). Removing one doesn't automatically remove the other.
The quick fix
Upload the PDF to unlock PDF. Enter the password. Flint saves an unencrypted copy. Download it — the new file opens without a password ever again.
The original file stays as-is. Keep both or delete the original after confirming the new one works.
If that didn't work
If you have the user password but not the owner password, you can open but not remove restrictions. Removing the user password is possible (Flint does it), but owner-set restrictions like 'no copy' may persist. To clear those, you need the owner password.
For PDFs where you've lost the password entirely, removal isn't possible — there's no legitimate path to bypass strong PDF encryption. Contact the file's source for a fresh copy.
Prevent it next time
Don't password-protect documents unless you genuinely need to. When you do, store the password in a password manager linked to the file. And for files you'll share repeatedly, make an unencrypted master copy and password-protect only the distributed versions.
FAQ
Can I remove a PDF password I don't know?
No. Strong PDF encryption is mathematically secure. You need the original password to legitimately remove it. Lost passwords usually mean contacting the source for a fresh copy.
What's the difference between user and owner passwords?
User password is required to open the file. Owner password is required to change permissions (printing, editing, copying). A PDF can have one, both, or neither.
Does removing the password change the file content?
No. The visible content is identical. Only the encryption wrapper is removed.
Can I re-encrypt with a new password later?
Yes. Use Flint's password-protect-pdf tool to apply a new password to the unlocked file. Useful for changing passwords or applying a different protection scheme.
Have the password? Unlock in Flint and the file opens freely forever. No password? Contact the source.