Link to a UNC Path
User Pudong is trying to create a hyperlink to a file on a server share using a UNC path in Discourse. Initially, the link appears but doesn’t work when clicked. David suggests adding “file” to the “allowed href schemes” site setting, which resolves the issue for Pudong.
However, other users, including Pierre_GRAND and user2, report issues with the file scheme, with Discourse replacing it with https. Jomaxro confirms that adding custom schemes like ftp works, but not file. Codinghorror and jomaxro investigate further, but the issue persists.
Davidd discovers that using HTML syntax <a href="file://myfile">link</a> works, but the Markdown syntax does not. He also finds that the sanitizer treats links with three slashes (file:///) as invalid. User2 reports that this issue applies to Windows paths as well.
Ultimately, david concludes that the issue is due to a browser security restriction in Chrome 76 (July 2019), which blocks file:// links, and there’s nothing Discourse can do to resolve this.
Hello
I use Discourse as a Intranet Forum.
Now I try to make a Hyperlink to a file on a servershare (\\server.domain.local\share\file.txt).
When I create a link to a UNC path, it appears, but it does not work. When I click on the link nothing happens.
Thats the code I try in Discourse:
[My File] (file://///server.domain.local/share/file.txt)
Is there a way to create a Hyperlink to a UNC Path? Or is it generally not supported?
Have you added “file” to the allowed href schemes site setting?
Hi David
That does the trick 
Thank you!
It looks like the updated markdown renderer won’t convert file:// paths properly ( discourse 1.9.5 )
Hello,
I have added file to “allowed href schemes” but when I create a hyperlink using a file:// url, Discourse will post it with https instead of file.
Then when changing the https back to “file” it’s still opening a https link when clicking on it.
Is the “file” scheme supported in Discourse(I’m in v2.2.0.beta2 +5)?
br
@jomaxro can you verify we didn’t regress on href scheme support?
Why are there an unusual number of forward slashes in there? Shouldn’t it be the same pattern for all schemes?
No clue. As mentioned, I’ve never seen the file href before. I used 3 for my screenshot as that’s what I saw over on SO: https://stackoverflow.com/questions/12837024/href-file-doesnt-work. In any case, I tried 1 (just in case), 2 (normal), 3 (SO answer), 4, & 5 (example in OP) slashes, none worked.
Is there any update on this issue? I run in the same problem using latest version. File is not working as expected.
Hi, I’m trying to use local links to PDF documents on local shared network device. I run Discourse locally as a documentation tool. I have tried to add “file” in the href settings, but cannot get a working local link. Is there any way around this? Is this broken or am I doing it wrong?
We should check this again @jomaxro
Updated my sandbox to 2.3.0.beta1, still not able to get file to work. Re-confirmed other custom href schemes do still work.
It’s weird… <a href="file://myfile">link</a> works, but [link](file://myfile) does not. But both options work for other custom schemes as @jomaxro said 
Maybe something in the commonmark link internals is stripping out file:// specifically. A quick search doesn’t reveal anything obvious in the discourse codebase.
@user2 the workaround for now is to use the HTML syntax for your link
<a href="file://myfile">link</a>
Edit: even with that, we still have an issue with file:// protocols. It is very common for file paths to start with a / (signifying the root of the filesystem), so the link looks like file:///myfile. Our sanitizer doesn’t like the three slashes at the beginning, and treats the link as invalid.
Does this only apply for *NIX paths?
file://C:/file.f
file:///var/file.f
Opened a file in browser and I see file:///K:/file...., same on windows. But <a href="file://myfile">link</a> does not work either. Maybe it works on *nix based system but not on windows paths?
This
<a href="file://C:/test.log">test</a>
Gives
domain.tld/clicks/track?url=file%3A%2F%2FC%3A%2Ftest.log&post_id=1103&topic_id=345 ERR_UNSAFE_REDIRECT
Ci sono novità in merito? 
Sto ancora sbattendo la testa contro il muro qui. Qualcuno ha idea di come risolvere questo problema? 
Da Chrome 76 (luglio 2019), sembra che i link file:// siano ora completamente bloccati: Restrictions on File Urls – text/plain
Quindi, non credo ci sia nulla che Discourse possa fare al riguardo: si tratta di una restrizione di sicurezza del browser.