diff --git a/include/admin/comments.inc.php b/include/admin/comments.inc.php
index c14c8e1e..7ca7a539 100644
--- a/include/admin/comments.inc.php
+++ b/include/admin/comments.inc.php
@@ -13,7 +13,7 @@ $errormsg = array();
 $msg = array();
 
 if (isset($serendipity['POST']['formAction']) && $serendipity['POST']['formAction'] == 'multiDelete' && sizeof($serendipity['POST']['delete']) != 0 && serendipity_checkFormToken()) {
-    if ($serendipity['POST']['togglemoderate'] != '') {
+    if (($serendipity['POST']['togglemoderate'] ?? null) != '') {
         foreach ( $serendipity['POST']['delete'] as $k => $v ) {
             $ac = serendipity_approveComment((int)$k, (int)$v, false, 'flip');
             if ($ac > 0) {
@@ -54,7 +54,7 @@ if (isset($serendipity['GET']['adminAction']) && $serendipity['GET']['adminActio
     $comment['comment']   = trim($serendipity['POST']['comment']);
     $comment['name']      = $serendipity['POST']['name'];
     $comment['email']     = $serendipity['POST']['email'];
-    $comment['subscribe'] = $serendipity['POST']['subscribe'];
+    $comment['subscribe'] = $serendipity['POST']['subscribe'] ?? false;
     $comment['parent_id'] = $serendipity['POST']['replyTo'];
 
     if (!empty($comment['comment'])) {
@@ -131,7 +131,8 @@ if (isset($serendipity['GET']['adminAction']) && ($serendipity['GET']['adminActi
                       'body'      => $serendipity['POST']['comment'],
                       'url'       => $serendipity['POST']['url'],
                       'timestamp' => time(),
-                      'parent_id' => $serendipity['GET']['id']
+                      'parent_id' => $serendipity['GET']['id'],
+                      'id'        => null
             );
         }
 
diff --git a/include/functions_comments.inc.php b/include/functions_comments.inc.php
index 967785fd..7c00b4c2 100644
--- a/include/functions_comments.inc.php
+++ b/include/functions_comments.inc.php
@@ -367,7 +367,7 @@ function serendipity_printComments($comments, $parentid = 0, $depth = 0, $trace
 
             $comment['comment'] = (is_string($comment['body']) ? serendipity_specialchars(strip_tags($comment['body'])) : '');
             $comment['url']     = (is_string($comment['url']) ? strip_tags($comment['url']) : '');
-            $comment['link_delete'] = $serendipity['baseURL'] . 'comment.php?serendipity[delete]=' . $comment['id'] . '&serendipity[entry]=' . $comment['entry_id'] . '&serendipity[type]=comments&' . $formToken;
+            $comment['link_delete'] = $serendipity['baseURL'] . 'comment.php?serendipity[delete]=' . ($comment['id'] ?? '') . '&serendipity[entry]=' . ($comment['entry_id'] ?? '') . '&serendipity[type]=comments&' . $formToken;
 
             /* Fix invalid cases in protocoll part */
             if (!empty($comment['url'])) {
@@ -406,7 +406,7 @@ function serendipity_printComments($comments, $parentid = 0, $depth = 0, $trace
             }
 
             if (serendipity_userLoggedIn()) {
-                if ($comment['subscribed'] == 'true') {
+                if (($comment['subscribed'] ?? null) == 'true') {
                     if ($comment['status'] == 'approved') {
                         $comment['body'] .= '<div class="serendipity_subscription_on"><em>' . ACTIVE_COMMENT_SUBSCRIPTION . '</em></div>';
                     } else {
@@ -418,7 +418,7 @@ function serendipity_printComments($comments, $parentid = 0, $depth = 0, $trace
             }
 
             $_smartyComments[] = $comment;
-            if ($comment['id'] && $parentid !== VIEWMODE_LINEAR ) {
+            if (isset($comment['id']) && $comment['id'] && $parentid !== VIEWMODE_LINEAR ) {
                 serendipity_printComments($comments, $comment['id'], ($depth+1), ($trace . $i . '.'), $smarty_block, $smarty_file);
             }
         }
diff --git a/templates/2k11/admin/comments.inc.tpl b/templates/2k11/admin/comments.inc.tpl
index e7bf6b17..192ae1ba 100644
--- a/templates/2k11/admin/comments.inc.tpl
+++ b/templates/2k11/admin/comments.inc.tpl
@@ -135,11 +135,11 @@
                                 <dt>{$CONST.EMAIL}:</dt>
                                 <dd>{if empty($comment.email)}N/A{else}<a href="mailto:{$comment.email|escape}" title="{$comment.email|escape}">{$comment.email|escape|truncate:40:"&hellip;"}</a>{if $comment.subscribed == 'true'} <i>({$CONST.ACTIVE_COMMENT_SUBSCRIPTION})</i>{/if}{/if} {$comment.action_email}</dd>
                                 <dt>IP:</dt>
-                                <dd>{if empty($comment.ip)}N/A{else}{$comment.ip|escape}{/if} {$comment.action_ip}</dd>
+                                <dd>{if empty($comment.ip)}N/A{else}{$comment.ip|escape}{/if} {if isset($comment.action_ip)}{$comment.action_ip}{/if}</dd>
                                 <dt>URL:</dt>
-                                <dd>{if empty($comment.url)}N/A{else}<a href="{$comment.url|escape}" title="{$comment.url|escape}">{$comment.url|escape|truncate:40:"&hellip;"}</a> {/if} {$comment.action_url}</dd>
+                                <dd>{if empty($comment.url)}N/A{else}<a href="{$comment.url|escape}" title="{$comment.url|escape}">{$comment.url|escape|truncate:40:"&hellip;"}</a> {/if} {if isset($comment.action_url)}{$comment.action_url}{/if}</dd>
                                 <dt>{$CONST.REFERER}:</dt>
-                                <dd>{if empty($comment.referer)}N/A{else}<a href="{$comment.referer|escape}" title="{$comment.referer|escape}">{$comment.referer|escape|truncate:40:"&hellip;"}</a>{/if} {$comment.action_referer}</dd>
+                                <dd>{if empty($comment.referer)}N/A{else}<a href="{$comment.referer|escape}" title="{$comment.referer|escape}">{$comment.referer|escape|truncate:40:"&hellip;"}</a>{/if} {if isset($comment.action_referer)}{$comment.action_referer}{/if}</dd>
                             </dl>
                         </div>
 
@@ -163,7 +163,9 @@
                             <li><button class="button_link toggle_comment_full" type="button" data-href="#c{$comment.id}_full" title="{$CONST.TOGGLE_ALL}"><span class="icon-right-dir" aria-hidden="true"></span><span class="visuallyhidden"> {$CONST.TOGGLE_ALL}</span></button></li>
                         {/if}
                         </ul>
+                        {if isset($comment.action_more)}
                         {$comment.action_more}
+                        {/if}
                     </li>
                 {/foreach}
                 </ul>
diff --git a/templates/2k11/comments.tpl b/templates/2k11/comments.tpl
index 25f8a373..6d7c1d25 100644
--- a/templates/2k11/comments.tpl
+++ b/templates/2k11/comments.tpl
@@ -1,5 +1,5 @@
 {foreach from=$comments item=comment name="comments"}
-<article id="c{$comment.id}" class="serendipity_comment{if $entry.author == $comment.author} serendipity_comment_author_self{/if} {cycle values="odd,even"} {if $comment.depth > 8}commentlevel-9{else}commentlevel-{$comment.depth}{/if}">
+<article id="c{$comment.id}" class="serendipity_comment{if isset($entry.author) && $entry.author == $comment.author} serendipity_comment_author_self{/if} {cycle values="odd,even"} {if $comment.depth > 8}commentlevel-9{else}commentlevel-{$comment.depth}{/if}">
     <header class="clearfix">
         <h4{if 'spice_twitter_name'|array_key_exists:$comment and $comment.spice_twitter_name && $comment.spice_twitter_followme} class="short-heading"{/if}>{if $comment.url}<a href="{$comment.url}">{/if}{$comment.author|default:$CONST.ANONYMOUS}{if $comment.url}</a>{/if}{if 'spice_twitter_name'|array_key_exists:$comment and $comment.spice_twitter_name and not $comment.spice_twitter_followme} (<a href="{$comment.spice_twitter_url}"{if $comment.spice_twitter_nofollow} rel="nofollow"{/if}>@{$comment.spice_twitter_name}</a>){/if} {$CONST.ON} <time datetime="{$comment.timestamp|@serendipity_html5time}">{$comment.timestamp|@formatTime:$template_option.date_format}</time>:</h4>
     {if 'spice_twitter_name'|array_key_exists:$comment and $comment.spice_twitter_name && $comment.spice_twitter_followme}
@@ -21,7 +21,7 @@
     <footer>
         <time>{$comment.timestamp|@formatTime:'%H:%M'}</time>
         | <a class="comment_source_trace" href="#c{$comment.id}" title="{$CONST.TWOK11_PLINK_TITLE}">{$CONST.TWOK11_PLINK_TEXT}</a>
-    {if 'is_entry_owner'|array_key_exists:$entry and $entry.is_entry_owner}
+    {if isset($entry) and 'is_entry_owner'|array_key_exists:$entry and $entry.is_entry_owner}
         | <a class="comment_source_ownerlink" href="{$comment.link_delete}" title="{$CONST.COMMENT_DELETE_CONFIRM|@sprintf:$comment.id:$comment.author}">{$CONST.DELETE}</a>
     {/if}
 {if $template_option.refcomments == true}