My PDF opens without a password, so why does the merge tool say it is protected or encrypted?
A PDF can be encrypted without asking you for a password to open it. One kind of protection lets anyone read the file while restricting editing, copying or printing, and [[merge-pdf]] refuses every encrypted file rather than trying to get round it. The fix is an unrestricted copy from whoever owns the file, or removing the restriction yourself if the file is yours.
Two passwords, not one
The PDF format has two kinds of protection. An open password stops you seeing anything until you type it. An owner password is different: the file opens normally, but its author has limited what you may do afterwards, such as editing or extracting pages. In both cases the file really is encrypted, even if your reader never asked you for anything.
The second kind is common on bank statements, certificates issued by government or university systems, and invoices from large companies. That is why people are surprised to see a 'password-protected or encrypted' message on a file they opened a minute ago.
Why the tool does not get round it
Merging means copying pages into a new file, which is exactly what the restriction was put there to stop. Plenty of software can technically ignore it, but we chose not to: Merge PDFs refuses the file, names it, and leaves the decision to whoever has the right to make it.
What to do now
- If someone else issued the file, ask them for an unrestricted copy, or ask whether they accept the documents as separate attachments.
- If you created the file and added the protection, open it in the program that made it and save a new copy without protection.
- Once you have an unencrypted copy, add it to the list with the other files and finish the merge.
And if all you need is to send the document alongside others, you may not need to merge it at all: attach the protected file as it is, next to one merged file of everything else.
Common questions
One file was refused. Did I lose the rest of the list?
No. The message names only the refused file, and the others stay in the list ready to merge.
Does printing to PDF remove the restriction?
It works in some programs and the restriction itself blocks it in others. Only do it if you are allowed to modify the file.
How can I tell if a file is restricted?
Many readers show security settings in the document properties window, including whether editing or page extraction is allowed.