So I went to post a comment on this piece, only to get an error message—something I've never encountered before. Reloading the page reveals a blank rectangle that I'd assumed were deleted comments on older (2010 and previous) pieces, but that may instead be errors related to an issue @DaGrandDragonn had with glitching replies (see blank rectangles here, and the Epic Stack if someone else remembers where that was posted). I can't think of anything different I did to provoke it, but if anyone else knows (and can link to) known broken comments, we might be able to build a usable diagnostic profile.

In this case, I think I know what is happening. It would appear the comment thread was created, but not the comment itself. Which, if you're seeing this a lot, then there are a bunch of orphaned threads with no comments in them. That part is easily fixable. Figuring out how to prevent that will take a little bit more work.
-- BK

Okay, all orphaned comment threads have been removed, and code is now in place for the next update to fix this from happening again.

"DAAAAAD IT BROKE AGAAAAIN..!"

Fixed. I wish I knew how that happened. The way things are coded, no comment thread should be created if the comment wasn't created. WTH?
-- BK

Bad news: I still can't actually reply on that journal. :x

What's happening when you try?

"Oh, man!
An error occurred, and we could not save your comment.
Please try again later."

The only difference I can think of is using two line separator characters (
) to spell out the Markdown syntax for hotlinks:

!
[bracket alt text]
(parenthesize URL)
but that's never caused problems in any of my other posts.

That's really strange. Nothing has changed in code, so I don't know why that would suddenly start being a problem. Will it submit without the l-sep characters?
-- BK

Possibly, but without an 'edit' button I don't wanna go spamming imperfect posts.

Thorvald:

Possibly, but without an 'edit' button I don't wanna go spamming imperfect posts.

Fair.

Of course, there's the dev server you could try it on. I've got test journal posts on there you could comment on.
-- BK

Tested various combinations and it is the line break. Checked in general upload comments and it posts fine, so the error seems specific to journal comments.

Good to know. Gives me something to look into. Thank you.
-- BK

I've found another break-point: Writing my original comment on this piece, I hit the rating stars by accident, clicked again to remove them, and the post failed and produced an empty frame. Tested on the dev server and the same thing happens (see empty comments on "Large canvas demo"). This corrupts the widget for all subsequent post attempts and the page must be reloaded to clear it.

Thank you for the head's up. I'll add it to the to-do list. sigh
-- BK

Update: It seems Journal comments also have an issue with nonstandard characters. ALT+13 (♪) broke my initial replies on this journal.

Ugh, I'm so confused as to why. Those fields accept UTF-8 characters. headdesk
-- BK

This has been an issue for a while but I either forgot to mention or thought it was fixed: Adding and then removing a rating from a submission comment produces an error message on posting, but creates an empty post.

I shall add this to my bug list.

-- BK