I'm got a label that includes a link to a PDF document. The location of the file is on a LAN drive.
However, the link will NOT function when viewing the form. You can click on it, but nothing happens. I know the URL is correct because I can right click, copy link location and then past it into a new window and the file opens.
I'm using IE11, (I know chrome and firefox do not allow file:// links)
If I put that same link into link list in SharePoint, it works fine, so I know its not a SharePoint issue.
I don't have O365 so i can't duplicate this directly, but have you looked at the HTML of the form in Firebug or equivalent to see what's going on?
Also, if the form is being opened in a modal dialog (the default) I can imagine there being restrictions on simply navigating away to a new URL as that would implicitly quit the form without saving. You might have more luck if you try opening the PDF file in a new window or tab.
Thanks for the ideas. A couple of notes:
I did a bit of testing on our (on-premise) site on this.
I found that if you put a link in a form label (I assume a Nintex form?), depending on how you entered the link in the editor the normal link anchor was sometimes pretty heavily mucked-about, so that a simple link-
<a href="file://.../My%20Pictures/clipart/horse-cart.jpg" target="_blank">Test Link</a>
Adding the link manually in the HTML seemed to work better.
I tried putting the link into a label, and a rich text field. In both cases this did not work in Firefox, presumably because of cross-origin content loading rules, but it did work for me in IE11. Remember this is from an on-premise server though.