Some other applications can create PDF files and assign a password to them. Preview will ask for this password if needed.
However, with Mac OS X 10.3.3 or earlier, Preview might ask for a password even if the document isn't password-protected.
This message appears:
This is normal when a PDF file has been password-protected by its creator.
However, if other software (such as Adobe Reader) opens the file without asking for a password, use that application to view the PDF file for now. Update to Mac OS X 10.3.4 or later to avoid this issue.
Additional information
When you can't view a password-protected file in Preview, this icon appears instead of text:
A document's password is set by the document's creator, and isn't your user account password. Ask the creator for the password if you need it.
Important: Information about products not manufactured by Apple is provided for information purposes only, and does not constitute Apple's recommendation or endorsement. Please contact the vendor for additional information.
However, with Mac OS X 10.3.3 or earlier, Preview might ask for a password even if the document isn't password-protected.
This message appears:
"This PDF is password protected. Without a password, some operations with this document will be restricted. Operations allowed are listed with a check mark next to them below.
{list of options}
To enable more operations, enter a password."
This is normal when a PDF file has been password-protected by its creator.
However, if other software (such as Adobe Reader) opens the file without asking for a password, use that application to view the PDF file for now. Update to Mac OS X 10.3.4 or later to avoid this issue.
Additional information
When you can't view a password-protected file in Preview, this icon appears instead of text:
A document's password is set by the document's creator, and isn't your user account password. Ask the creator for the password if you need it.
Important: Information about products not manufactured by Apple is provided for information purposes only, and does not constitute Apple's recommendation or endorsement. Please contact the vendor for additional information.