Problem

After Confluence upgrade (issue has been noticed in upgrade past Confluence version 5.6.x and above), users are not able to add comments to any Confluence page with an Unknown macro: {voting-user-threshold} error message displayed above the comment field.

Sample screenshot of a Confluence page is shown below:

Diagnosis

Check if there are any customisations applied in your Confluence instance by logging in with Admin user and following the steps below:

1. Navigate to Confluence Admin >> Layouts to check if there're any customised layouts configured in your instance.
2. Next,  check for any custom CSS applied in your Confluence by navigating to Confluence Admin >> Stylesheet page. 
3. Once you've done this, access Confluence Admin >> Themes page and check if you're using any custom themes in your Confluence instance.

4. Lastly, check if there're any Custom HTML in your Confluence instance by accessing the Confluence Admin >> Custom HTML page.

Cause

Following the steps above, you'd noticed that there's customised Comments Layout applied in your Confluence instance.

Looking closely at the Comments Layout script, it looks like there are some integration with a third-party plugin - Content Voting macro by Adaptavist in the script itself which had caused this issue.

Please refer to the script snippet below:

...
	        #if ($commentActionSection == 'primary')
   #end		            <li >$action.helper.renderConfluenceMacro("{content-voting-controls:id=$commentId}")</li>
        #end
    </ul>
...
	                </a>
     #end		            </h2>
            <a title="$i18n.getText('comments.show.hide')" href="#" 
## Happens when you try to edit a comment that doesn't exist		               class="comments-show-hide icon #if($action.commentsShowing)comments-showing icon-section-opened#else icon-section-closed#end">
     #if ($action.editComment && !$action.comment)		                $i18n.getText("comments.show.hide")
         #applyDecorator ("message")		            </a>
             #decoratorParam("type" "error")		            $action.helper.renderConfluenceMacro("{voting-user-threshold}")
             $action.getText("comment.edit.not.found")		        </div>
         #end		    #end

Resolution

To resolve this issue please remove the customised Comments Layout by doing the following:

1. Navigate through Confluence Administration page >> Layouts.
2. Then, click on Reset Default for Comments Layout under Contents Layout section.