I am unable to access a chat room on conpherence that I am a member of, it is throwing the following error:

Hi @Mine0901, to understand correctly:
You click this very link here:
https://phabricator.wikimedia.org/conpherence/519/
and you end up on a page that displays "Unhandled Exception("Exception"): Rejecting ambiguous URI" ?
When you end up on that page, what is the link shown in the address bar of your browser?
Could you attach a screenshot of that situation (but please make sure that no private / confidential data is displayed in that screenshot before uploading it here)?

The link remains the same. Please find the screenshot

How weird.
Is it the same problem when trying to access via the URL https://phabricator.wikimedia.org/Z519 ?
Thinking about a workaround, if you go to https://phabricator.wikimedia.org/conpherence/ , do you see the room listed in left pane and can you access it (I guess not)?
Do you know if somebody else (who is in/has access to that Conpherence room) has the same problem?

Yes, I have access to the room and get the same error. It doesn't matter
whether access is by direct link or by the link from phabricator.

What I expect has happened is that phabricator is correctly recognising the
input as a link, and tries to create a hyperlink out of it. But something
else in the link parsing apparatus is throwing an exception and causing a
500 internal server error.

This T166958 is also related.

In T166870#3311680, @Mvolz wrote:

Yes, I have access to the room and get the same error. It doesn't matter
whether access is by direct link or by the link from phabricator.

What I expect has happened is that phabricator is correctly recognising the
input as a link, and tries to create a hyperlink out of it. But something
else in the link parsing apparatus is throwing an exception and causing a
500 internal server error.

The fix i have is that it will make it plain text. It's better then having it throw an error.

This should now be fixed upstream (https://secure.phabricator.com/T12796), see that task for a description and a more narrow reproduction case.

This should be fixed by 51e0045c4506d0a0d40db7c0c8a787edce3c7bcd

@mmodell hi, your fix does not fix the error here T166958 i am running your fix on phab-01 and see this https://phab-01.wmflabs.org/T145

"Rejecting ambiguous URI". This URI is not formatted or encoded properly."

@mmodell i re deployed https://phabricator.wikimedia.org/D679 and that fixes it.

Thanks, we are now able to access the room :).

Still an issue, see T168942

@Aklapper: I fear this will keep popping up in different places, we have to play whack-a-mole until all call sites are found and try/catch is added.

Ah, I see what happened - for some reason libphutil got reverted to an older revision. Fixed