Merge branch 'master' into next

diff --cc files/lib/page/ConversationListPage.class.php
index cf81299719f41e19e87c8d34ab8a3bd39b52e710,a35f918ae326c9087cd399e7c8a76933fca77016..282629883e3c4625603a5dfdea8d6b5b9949becc
--- 1/files/lib/page/ConversationListPage.class.php
--- 2/files/lib/page/ConversationListPage.class.php
+++ b/files/lib/page/ConversationListPage.class.php
@@@ -157,15 -141,25 +157,26 @@@ class ConversationListPage extends Sort
        }
        
        /**
 -       * @see \wcf\page\IPage::readData()
 +       * @inheritDoc
         */
        public function readData() {
+               // if sort field is `username`, `conversation.` has to prepended because `username`
+               // alone is ambiguous 
+               if ($this->sortField === 'username') {
+                       $this->sortField = 'conversation.username';
+               }
+               
                parent::readData();
                
+               // change back to old value
+               if ($this->sortField === 'conversation.username') {
+                       $this->sortField = 'username';
+               }
+               
                if ($this->filter != '') {
                        // add breadcrumbs
 -                      WCF::getBreadcrumbs()->add(new Breadcrumb(WCF::getLanguage()->get('wcf.conversation.conversations'), LinkHandler::getInstance()->getLink('ConversationList')));
 +                      // TODO: this is not working at the moment as PageLocationManager already sets this as the current page based on request data which is later discarded 
 +                      PageLocationManager::getInstance()->addParentLocation('com.woltlab.wcf.conversation.ConversationList');
                }
                
                // read stats