Currently it is not possible to open password protected PDF files in the WebUI. The problem is that there is no message saying that the file is password protected and cannot be opened therefore. The webui seems to load the file forever.
@Jonathan @daniel.pan Please consider adding a freature that allows to open password protected PDF files. At a minimum show a message that informs the user that the pdf file is password protected and cannot be viewed therefore. This message could already be shown when selecting the file, blocking opening it in a new tab at that point already.