I note a few posts (4 for example) for multi citation, I press the button "Reply to Thread" and answer.

In this case, a tick (previously marked) remain active. https://vborg.vbsupport.ru/external/2015/04/7.jpg

They should be removed after the answer. https://vborg.vbsupport.ru/external/2015/04/8.jpg

Yes,when I reply, they are all unmarked for multi-quote just as they should be. Are you actually submitting the reply?

If so, try disabling the product, and see if this behavior persists...

Behavior persists even when turned off.
Starts to work properly only after hack deleted

The earliest version of vBulletin to which I have access is 4.2.0 PL3, and it behaves correctly just as vB 4.2.1 and vB 4.2.2 PL 4 do.

If other users of vB 4.1.x report this issue, then I will mark this product for 4.2.x only.

I'm getting the following error:
Any idea how to resolve this?

Edit: I'm on 4.2.2

Did you upload the contents of the "upload" folder to your forum's root directory (where forum.php resides)?

edit: To everyone asking for support, please click "Mark As Installed." :D

Oh. Thank you, I feel pretty silly now. Works great!

Marked as installed.

Maybe you can help this file
P.S. Marked as installed. Nominate for Modification of the Month

This product is not working properly in these versions, check.

I don't use the quick edit option because on the forums with which I am involved we use LaTeX rendering by MathJax, and the quick reply/edit simply do not work well with it. My users like for their LaTeX to be rendered after posting or making an edit without having to manually refresh the page.

However, when I enable the quick reply on my local dev site, I do see the behavior you have indicated. but I see this behavior even with my product uninstalled. I must therefore conclude that it is behavior intrinsic to vBulletin 4.2.x. As I said above, I don't have access to vBulletin 4.1.x and so I can't say whether that version behaves in this way or not.