I am attempting to redact a large pdf file. When I open the file, it has a bar across the top with the message "please fill out the following form". I can mark redactions, but when I attempt to apply them I get a message saying, "In order to proceed Digital Signatures must be removed and the document must be fully authorized. Do you want to make these changes and continue?" I click "ok". Then I get a message saying, "an internal error occurred." How do I get around this problem?
You cannot redact a signed document. This is because one of the things signatures guarantee is access to the OLDER document (i.e. there will be an unredacted copy in there).
In general you cannot remove signatures, but sometimes you can. Look under the Signatures tab (right click on left vertical bar if there isn't one) to see if it is removable.