diff --git a/src/admin/templates/admins.edit.tpl b/src/admin/templates/admins.edit.tpl
index 5eac201..d34dc41 100644
--- a/src/admin/templates/admins.edit.tpl
+++ b/src/admin/templates/admins.edit.tpl
@@ -36,7 +36,7 @@
 				<td class="td1" width="220">{lng p="areas"}:</td>
 				<td class="td2">
 					{foreach from=$permsTable item=permTitle key=permName}
-					<input type="checkbox" name="perms[{$permName}]" value="1" id="perm_{$permName}"{if $admin.perms.$permName} checked="checked"{/if} />
+					<input type="checkbox" name="perms[{$permName}]" value="1" id="perm_{$permName}"{if isset($admin.perms.$permName) &&  $admin.perms.$permName} checked="checked"{/if} />
 					<label for="perm_{$permName}" style="font-weight:bold;">{$permTitle}</label><br />
 					{/foreach}
 				</td>
@@ -45,7 +45,7 @@
 				<td class="td1">{lng p="plugins"}:</td>
 				<td class="td2">
 					{foreach from=$pluginList item=pluginTitle key=pluginName}
-					<input type="checkbox" name="perms[plugins][{$pluginName}]" value="1" id="plugin_{$pluginName}"{if $admin.perms.plugins.$pluginName} checked="checked"{/if} />
+					<input type="checkbox" name="perms[plugins][{$pluginName}]" value="1" id="plugin_{$pluginName}"{if isset($admin.perms.plugins.$pluginName) && $admin.perms.plugins.$pluginName} checked="checked"{/if} />
 					<label for="plugin_{$pluginName}" style="font-weight:bold;">{text value=$pluginTitle}</label><br />
 					{/foreach}
 				</td>
diff --git a/src/admin/templates/logs.tpl b/src/admin/templates/logs.tpl
index 2abe1e6..0888c08 100644
--- a/src/admin/templates/logs.tpl
+++ b/src/admin/templates/logs.tpl
@@ -46,19 +46,19 @@
 			<tr>
 				<td class="td1">{lng p="priority"}:</td>
 				<td class="td2">
-					<input type="checkbox"{if $prio[8]} checked="checked"{/if} name="prio[8]" id="prio8" />
+					<input type="checkbox"{if isset($prio[8])} checked="checked"{/if} name="prio[8]" id="prio8" />
 					<label for="prio8"><img src="{$tpldir}images/debug.png" border="0" alt="" width="16" height="16" /></label> &nbsp; 
 					
-					<input type="checkbox"{if $prio[2]} checked="checked"{/if} name="prio[2]" id="prio2" />
+					<input type="checkbox"{if isset($prio[2])} checked="checked"{/if} name="prio[2]" id="prio2" />
 					<label for="prio2"><img src="{$tpldir}images/info.png" border="0" alt="" width="16" height="16" /></label> &nbsp; 
 					
-					<input type="checkbox"{if $prio[1]} checked="checked"{/if} name="prio[1]" id="prio1" />
+					<input type="checkbox"{if isset($prio[1])} checked="checked"{/if} name="prio[1]" id="prio1" />
 					<label for="prio1"><img src="{$tpldir}images/warning.png" border="0" alt="" width="16" height="16" /></label> &nbsp; 
 					
-					<input type="checkbox"{if $prio[4]} checked="checked"{/if} name="prio[4]" id="prio4" />
+					<input type="checkbox"{if isset($prio[4])} checked="checked"{/if} name="prio[4]" id="prio4" />
 					<label for="prio4"><img src="{$tpldir}images/error.png" border="0" alt="" width="16" height="16" /></label> &nbsp; 
 					
-					<input type="checkbox"{if $prio[16]} checked="checked"{/if} name="prio[16]" id="prio16" />
+					<input type="checkbox"{if isset($prio[16])} checked="checked"{/if} name="prio[16]" id="prio16" />
 					<label for="prio16"><img src="{$tpldir}images/plugin.png" border="0" alt="" width="16" height="16" /></label>
 				</td>
 			</tr>
diff --git a/src/admin/templates/msg.tpl b/src/admin/templates/msg.tpl
index 096fff6..cf2ea84 100644
--- a/src/admin/templates/msg.tpl
+++ b/src/admin/templates/msg.tpl
@@ -23,10 +23,8 @@
 	{/if}
 </fieldset>
 
-{if isset($reloadMenu)}
+{if isset($reloadMenu) && $reloadMenu}
 <script>
-<!--
 	parent.frames['menu'].location.href = 'main.php?action=menu&item=4&sid={$sid}';
-//-->
 </script>
-{/if}
+{/if}
\ No newline at end of file
diff --git a/src/admin/templates/plugins.list.tpl b/src/admin/templates/plugins.list.tpl
index e22a02c..a9e2802 100644
--- a/src/admin/templates/plugins.list.tpl
+++ b/src/admin/templates/plugins.list.tpl
@@ -47,7 +47,7 @@
 	</table>
 </fieldset>
 
-{if $reloadMenu}
+{if isset($reloadMenu)}
 <script>
 <!--
 	parent.frames['menu'].location.href = 'main.php?action=menu&item=4&sid={$sid}';
diff --git a/src/admin/templates/prefs.languages.texts.tpl b/src/admin/templates/prefs.languages.texts.tpl
index 845bf10..13cffbf 100644
--- a/src/admin/templates/prefs.languages.texts.tpl
+++ b/src/admin/templates/prefs.languages.texts.tpl
@@ -48,9 +48,9 @@
 			<td><img src="{$tpldir}images/phrases.png" border="0" alt="" width="16" height="16" /></td>
 			<td><a name="{$text.key}" />{$text.title}<br /><small>{text value=$text.key}</small></td>
 			<td>
-				{if $customTextsHTML[$text.key]}<div style="border: 1px solid #DDDDDD;background-color:#FFFFFF;">{/if}
-				<textarea onfocus="this.style.height='240px';" onblur="this.style.height='100px';" style="width:99%;height:{if $customTextsHTML[$text.key]}350{else}100{/if}px;" name="text-{$text.key}" id="text-{$text.key}">{text value=$text.text allowEmpty=true}</textarea>
-				{if $customTextsHTML[$text.key]}
+				{if isset($customTextsHTML[$text.key])}<div style="border: 1px solid #DDDDDD;background-color:#FFFFFF;">{/if}
+				<textarea onfocus="this.style.height='240px';" onblur="this.style.height='100px';" style="width:99%;height:{if isset($customTextsHTML[$text.key])}350{else}100{/if}px;" name="text-{$text.key}" id="text-{$text.key}">{text value=$text.text allowEmpty=true}</textarea>
+				{if isset($customTextsHTML[$text.key])}
 				</div>
 				<script>
 				<!--
diff --git a/src/serverlib/calendar.class.php b/src/serverlib/calendar.class.php
index 00d9d1b..d594d6a 100644
--- a/src/serverlib/calendar.class.php
+++ b/src/serverlib/calendar.class.php
@@ -761,7 +761,7 @@ class BMCalendar
         $html .= sprintf('		<th class="Caption" colspan="7"><a href="organizer.calendar.php?view=month&date=%d&sid=%s">%s</a></th>'."\n",
             mktime(0, 0, 0, $month, 1, $year),
             session_id(),
-            _strftime('%B %Y', mktime(0, 0, 0, $month, 1, $year)));
+            date('F Y', mktime(0, 0, 0, $month, 1, $year)));
         $html .= '	</tr>'."\n";
 
         // column headings
diff --git a/src/serverlib/common.inc.php b/src/serverlib/common.inc.php
index 23e325d..c33ac92 100644
--- a/src/serverlib/common.inc.php
+++ b/src/serverlib/common.inc.php
@@ -1702,7 +1702,7 @@ function categorizeDate($date)
 		$ts[$a] = array(
 			'from' 	=> $last,
 			'to'	=> $last+86400,
-			'text' 	=> _strftime('%A', $last),
+			'text' 	=> date('l', $last),
 			'date' 	=> $last
 		);
 	}
@@ -3519,7 +3519,7 @@ function b1gMailShutdown()
  * @param string $file
  * @param int $line
  */
-function DisplayError($number, $title, $description, $text = false, $file, $line)
+function DisplayError($number, $title, $description, $text = false, $file = '', $line = '')
 {
 	if(INTERFACE_MODE)
 	{
diff --git a/src/serverlib/mailbox.class.php b/src/serverlib/mailbox.class.php
index b7ed15a..7f9ffa9 100644
--- a/src/serverlib/mailbox.class.php
+++ b/src/serverlib/mailbox.class.php
@@ -799,7 +799,7 @@ class BMMailbox
 	 *
 	 * @return array
 	 */
-	function GetDropdownFolderList($parent = -1, &$result, $level = 0, $more = 0, $includeShared = true)
+	function GetDropdownFolderList($parent = -1, &$result = null, $level = 0, $more = 0, $includeShared = true)
 	{
 		global $db, $lang_user;
 
diff --git a/src/serverlib/string.inc.php b/src/serverlib/string.inc.php
index 41ae942..6a443fc 100644
--- a/src/serverlib/string.inc.php
+++ b/src/serverlib/string.inc.php
@@ -36,7 +36,11 @@ function Strip4ByteChars($in)
 
 	}
 	else if(in_array(strtolower($currentCharset), array('utf8', 'utf-8')))
-		return preg_replace('/[\x{10000}-\x{10FFFF}]/u', ' ', $in);
+        // It is possible that the provided string is actually not an UTF8 string. In this case, preg_replace will return null.
+        $result = preg_replace('/[\x{10000}-\x{10FFFF}]/u', ' ', $in);
+        if (!is_null($result)) {
+            return $result;
+        }
 
 	return $in;
 }
diff --git a/src/serverlib/user.class.php b/src/serverlib/user.class.php
index c750582..427ed0b 100644
--- a/src/serverlib/user.class.php
+++ b/src/serverlib/user.class.php
@@ -534,7 +534,7 @@ class BMUser
 	 * @param int $userID User ID
 	 * @param string $resetKey Reset key
 	 */
-	public function ResetPassword($userID, $resetKey)
+	public static function ResetPassword($userID, $resetKey)
 	{
 		global $db;
 
diff --git a/src/templates/modern/li/email.folders.edit.tpl b/src/templates/modern/li/email.folders.edit.tpl
index 3d3da57..6d6883b 100644
--- a/src/templates/modern/li/email.folders.edit.tpl
+++ b/src/templates/modern/li/email.folders.edit.tpl
@@ -1,20 +1,20 @@
 <div id="contentHeader">
 	<div class="left">
 		<i class="fa fa-folder-o" aria-hidden="true"></i>
-		{if $folder}{lng p="editfolder"}{else}{lng p="addfolder"}{/if}
+		{if isset($folder)}{lng p="editfolder"}{else}{lng p="addfolder"}{/if}
 	</div>
 </div>
 
 <div class="scrollContainer"><div class="pad">
-<form name="f1" method="post" action="email.folders.php?action={if $folder}saveFolder&id={$folder.id}{else}createFolder{/if}&sid={$sid}" onsubmit="{if $folder && $folder.intelligent==1}if(!formSubmitOK) {literal}{ parent.frames.condition_frame.document.forms.saveForm.elements.submitParent.value='1';parent.frames.condition_frame.document.forms.saveForm.submit();return(false); }{/literal}{/if}return(checkFolderForm(this));">
+<form name="f1" method="post" action="email.folders.php?action={if isset($folder)}saveFolder&id={$folder.id}{else}createFolder{/if}&sid={$sid}" onsubmit="{if isset($folder) && $folder.intelligent==1}if(!formSubmitOK) {literal}{ parent.frames.condition_frame.document.forms.saveForm.elements.submitParent.value='1';parent.frames.condition_frame.document.forms.saveForm.submit();return(false); }{/literal}{/if}return(checkFolderForm(this));">
 	<table class="listTable">
 		<tr>
-			<th class="listTableHead" colspan="2"> {if $folder}{lng p="editfolder"}{else}{lng p="addfolder"}{/if}</th>
+			<th class="listTableHead" colspan="2"> {if isset($folder)}{lng p="editfolder"}{else}{lng p="addfolder"}{/if}</th>
 		</tr>
 		<tr>
 			<td class="listTableLeft">* <label for="titel">{lng p="title"}:</label></td>
 			<td class="listTableRight">
-				<input type="text" name="titel" id="titel" value="{if isset($folder.titel)}{text value=$folder.titel allowEmpty=true}{/if}" style="width:100%;" />
+				<input type="text" name="titel" id="titel" value="{text value=$folder.titel|default:'' allowEmpty=true}" style="width:100%;" />
 			</td>
 		</tr>
 		<tr>
@@ -23,7 +23,7 @@
 				<select name="parentfolder" id="parentfolder">
 					<option value="-1">------------</option>
 				{foreach from=$dropdownFolderList key=dFolderID item=dFolderTitle}{if $dFolderID>0&&$dFolderID!=$folder.id}
-					<option value="{$dFolderID}" style="font-family:courier;"{if $folder.parent==$dFolderID} selected="selected"{/if}>{$dFolderTitle}</option>
+					<option value="{$dFolderID}" style="font-family:courier;"{if isset($folder) && $folder.parent==$dFolderID} selected="selected"{/if}>{$dFolderTitle}</option>
 				{/if}{/foreach}
 				</select>
 			</td>
@@ -31,32 +31,32 @@
 		<tr>
 			<td class="listTableLeft"><label for="storetime">{lng p="storetime"}:</label></td>
 			<td class="listTableRight">
-				<select name="storetime" id="storetime"{if $folder&&$folder.intelligent==1} disabled="disabled"{/if}>
+				<select name="storetime" id="storetime"{if isset($folder) && $folder.intelligent==1} disabled="disabled"{/if}>
 					<option value="-1">------------</option>
-					<option value="86400"{if $folder.storetime==86400} selected="selected"{/if}>1 {lng p="days"}</option>
-					<option value="172800"{if $folder.storetime==172800} selected="selected"{/if}>2 {lng p="days"}</option>
-					<option value="432000"{if $folder.storetime==432000} selected="selected"{/if}>5 {lng p="days"}</option>
-					<option value="604800"{if $folder.storetime==604800} selected="selected"{/if}>7 {lng p="days"}</option>
-					<option value="1209600"{if $folder.storetime==1209600} selected="selected"{/if}>2 {lng p="weeks"}</option>
-					<option value="2419200"{if $folder.storetime==2419200} selected="selected"{/if}>4 {lng p="weeks"}</option>
-					<option value="4838400"{if $folder.storetime==4838400} selected="selected"{/if}>2 {lng p="months"}</option>
+					<option value="86400"{if isset($folder) && $folder.storetime==86400} selected="selected"{/if}>1 {lng p="days"}</option>
+					<option value="172800"{if isset($folder) && $folder.storetime==172800} selected="selected"{/if}>2 {lng p="days"}</option>
+					<option value="432000"{if isset($folder) && $folder.storetime==432000} selected="selected"{/if}>5 {lng p="days"}</option>
+					<option value="604800"{if isset($folder) && $folder.storetime==604800} selected="selected"{/if}>7 {lng p="days"}</option>
+					<option value="1209600"{if isset($folder) && $folder.storetime==1209600} selected="selected"{/if}>2 {lng p="weeks"}</option>
+					<option value="2419200"{if isset($folder) && $folder.storetime==2419200} selected="selected"{/if}>4 {lng p="weeks"}</option>
+					<option value="4838400"{if isset($folder) && $folder.storetime==4838400} selected="selected"{/if}>2 {lng p="months"}</option>
 				</select>
 			</td>
 		</tr>
 		<tr>
 			<td class="listTableLeft"><label for="subscribed">{lng p="subscribed"}?</label></td>
 			<td class="listTableRight">
-				<input type="checkbox" id="subscribed" name="subscribed" {if !$folder || $folder.subscribed==1}checked="checked" {/if}/>
+				<input type="checkbox" id="subscribed" name="subscribed" {if !isset($folder) || $folder.subscribed==1}checked="checked" {/if}/>
 			</td>
 		</tr>
 		<tr>
 			<td class="listTableLeft"><label for="intelligent">{lng p="intelligent"}:</label></td>
 			<td class="listTableRight">
-				<input type="checkbox" id="intelligent" name="intelligent" {if $folder}readonly="readonly" disabled="disabled" {/if}{if $folder.intelligent==1}checked="checked" {/if}/>
+				<input type="checkbox" id="intelligent" name="intelligent" {if isset($folder)}readonly="readonly" disabled="disabled" {if $folder.intelligent==1}checked="checked" {/if}{/if}/>
 			</td>
 		</tr>
 		
-		{if $folder && $folder.intelligent}
+		{if isset($folder) && $folder.intelligent}
 		<tr>
 			<td class="listTableLeft">* {lng p="conditions"}:</td>
 			<td class="listTableRight">
@@ -82,5 +82,4 @@
 		</tr>
 	</table>
 </form>
-</div></div> 
-
+</div></div> 
\ No newline at end of file
diff --git a/src/templates/modern/li/organizer.addressbook.edit.tpl b/src/templates/modern/li/organizer.addressbook.edit.tpl
index e311864..2957f8a 100644
--- a/src/templates/modern/li/organizer.addressbook.edit.tpl
+++ b/src/templates/modern/li/organizer.addressbook.edit.tpl
@@ -1,28 +1,28 @@
 <div id="contentHeader">
 	<div class="left">
 		<i class="fa fa-address-book-o" aria-hidden="true"></i>
-		{if isset($contact)}{lng p="editcontact"}{else}{lng p="addcontact"}{/if}
+		{if isset($contact) && $contact}{lng p="editcontact"}{else}{lng p="addcontact"}{/if}
 	</div>
 </div>
 
 <div class="scrollContainer"><div class="pad">
 
-<form name="f1" method="post" action="organizer.addressbook.php?action={if $contact}saveContact&id={$contact.id}{else}createContact{/if}&sid={$sid}" onsubmit="return(checkContactForm(this));">
+<form name="f1" method="post" action="organizer.addressbook.php?action={if isset($contact) && $contact}saveContact&id={$contact.id}{else}createContact{/if}&sid={$sid}" onsubmit="return(checkContactForm(this));">
 	<input type="hidden" id="submitAction" name="submitAction" value="" />
 	<table class="listTable">
 		<tr>
-			<th class="listTableHead" colspan="3"> {if isset($contact)}{lng p="editcontact"}{else}{lng p="addcontact"}{/if}</th>
+			<th class="listTableHead" colspan="3"> {if isset($contact) && $contact}{lng p="editcontact"}{else}{lng p="addcontact"}{/if}</th>
 		</tr>
 		<tr>
 			<td class="listTableLeftDesc"><i class="fa fa-address-card-o" aria-hidden="true"></i></td>
 			<td class="listTableRightDesc">{lng p="common"}</td>
 			
-			<td class="listTableRightest" rowspan="26" width="180">				
+			<td class="listTableRightest" rowspan="26" width="220">				
 				<fieldset>
 					<legend>{lng p="userpicture"}</legend>
 					<input type="hidden" name="pictureFile" id="pictureFile" value="" />
 					<input type="hidden" name="pictureMime" id="pictureMime" value="" />
-					<br /><center><div id="pictureDiv" style="background-size: cover; background-position: center center; background-repeat: no-repeat; background-image: url({if empty($contact.picture)}{$tpldir}images/li/no_picture.png{else}organizer.addressbook.php?action=addressbookPicture&id={$contact.id}&sid={$sid}{/if}); width: 80px; height: 80px;"><a href="javascript:addrUserPicture({if $contact}{$contact.id}{else}-1{/if});"><img src="{$tpldir}images/li/pic_frame.gif" width="80" height="80" border="0" alt="" /></a></div></center>
+					<br /><center><div id="pictureDiv" style="background-size: cover; background-position: center center; background-repeat: no-repeat; background-image: url({if !isset($contact) || !$contact || $contact.picture==''}{$tpldir}images/li/no_picture.png{else}organizer.addressbook.php?action=addressbookPicture&id={$contact.id}&sid={$sid}{/if}); width: 80px; height: 80px;"><a href="javascript:addrUserPicture({if isset($contact) && $contact}{$contact.id}{else}-1{/if});"><img src="{$tpldir}images/li/pic_frame.gif" width="80" height="80" border="0" alt="" /></a></div></center>
 					<br /><small>{lng p="changepicbyclick"}</small>
 				</fieldset>
 				<small><br /></small>				
@@ -44,7 +44,7 @@
 				<fieldset>
 					<legend>{lng p="features"}</legend>
 					<div align="left">
-						{if isset($contact)}
+						{if isset($contact) && $contact}
 							<a href="javascript:addrFunction('exportVCF');"><i class="fa fa-address-card-o" aria-hidden="true"></i> {lng p="exportvcf"}</a><br />
 							<a href="javascript:addrFunction('selfComplete');"><i class="fa fa-check-square-o" aria-hidden="true"></i> {lng p="complete"}</a><br />
 							<a href="javascript:addrFunction('intelliFolder');"><i class="fa fa-folder" aria-hidden="true"></i> {lng p="convfolder"}</a><br />
@@ -62,8 +62,8 @@
 			<td class="listTableRight">
 				<select name="anrede" id="anrede">
 					<option value=""{if empty($contact.anrede)} selected="selected"{/if}>&nbsp;</option>
-					<option value="frau"{if $contact.anrede=='frau'} selected="selected"{/if}>{lng p="mrs"}</option>
-					<option value="herr"{if $contact.anrede=='herr'} selected="selected"{/if}>{lng p="mr"}</option>
+					<option value="frau"{if isset($contact) && $contact.anrede=='frau'} selected="selected"{/if}>{lng p="mrs"}</option>
+					<option value="herr"{if isset($contact) && $contact.anrede=='herr'} selected="selected"{/if}>{lng p="mr"}</option>
 				</select>
 			</td>
 		</tr>
@@ -83,7 +83,7 @@
 						<td>{lng p="priv"}</td>
 						<td align="right">
 							<label for="default_priv">{lng p="default"}</label>
-							<input type="radio" name="default" id="default_priv" value="priv"{if $contact.default_address!=2} checked="checked"{/if} />
+							<input type="radio" name="default" id="default_priv" value="priv"{if !isset($contact) || $contact.default_address!=2} checked="checked"{/if} />
 						</td>
 					</tr>
 				</table>
diff --git a/src/templates/modern/li/organizer.calendar.showdate.tpl b/src/templates/modern/li/organizer.calendar.showdate.tpl
index 3104082..2ba579b 100644
--- a/src/templates/modern/li/organizer.calendar.showdate.tpl
+++ b/src/templates/modern/li/organizer.calendar.showdate.tpl
@@ -1,23 +1,20 @@
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<!DOCTYPE html>
 
-<html xmlns="http://www.w3.org/1999/xhtml">
+<html>
 
 <head>
-    <title>{text value=$date.title}</title>
+  <title>{text value=$date.title}</title>
     
-	<!-- meta -->
 	<meta http-equiv="content-type" content="text/html; charset={$charset}" />
 	
-	<!-- links -->
-	<link rel="shortcut icon" type="image/png" href="res/favicon.png" />
+	<link rel="shortcut icon" type="image/png" href="{$tpldir}res/favicon.png" />
 	<link href="{$tpldir}style/dialog.css" rel="stylesheet" type="text/css" />
 	
-	<!-- client scripts -->
-	<script src="clientlang.php" type="text/javascript"></script>
-	<script src="clientlib/overlay.js" type="text/javascript"></script>
-	<script src="{$tpldir}js/common.js" type="text/javascript"></script>
-	<script src="{$tpldir}js/loggedin.js" type="text/javascript"></script>
-	<script src="{$tpldir}js/dialog.js" type="text/javascript"></script>
+	<script src="clientlang.php"></script>
+	<script src="{$tpldir}clientlib/overlay.js"></script>
+	<script src="{$tpldir}js/common.js"></script>
+	<script src="{$tpldir}js/loggedin.js"></script>
+	<script src="{$tpldir}js/dialog.js"></script>
 </head>
 
 <body>
@@ -52,11 +49,11 @@
 			</tr>
 			<tr>
 				<td><b>{lng p="reminder"}:</b> &nbsp;</td>
-				<td><input type="checkbox"{if ($date.flags&(2|4|8))} checked="checked"{/if} disabled="disabled" /></td>
+				<td><input type="checkbox" {if (isset($date.flags) && (($date.flags&2) || ($date.flags&4) || $date.flags&8))} checked="checked"{/if} disabled="disabled" /></td>
 			</tr>
 			<tr>
 				<td><b>{lng p="repeating"}:</b> &nbsp;</td>
-				<td><input type="checkbox"{if $date.repeat_flags!=0} checked="checked"{/if} disabled="disabled" /></td>
+				<td><input type="checkbox" {if $date.repeat_flags!=0} checked="checked"{/if} disabled="disabled" /></td>
 			</tr>
 		</table>
 	</fieldset>
@@ -102,4 +99,4 @@
 	</div>
 </body>
 
-</html>
+</html>
\ No newline at end of file
diff --git a/src/templates/modern/li/organizer.todo.edit.tpl b/src/templates/modern/li/organizer.todo.edit.tpl
index 86f2733..6910e0d 100644
--- a/src/templates/modern/li/organizer.todo.edit.tpl
+++ b/src/templates/modern/li/organizer.todo.edit.tpl
@@ -6,17 +6,17 @@
 </div>
 
 <div class="scrollContainer"><div class="pad">
-<form name="f1" method="post" action="organizer.todo.php?action={if $task}saveTask&id={$task.id}{else}createTask{/if}&sid={$sid}" onsubmit="return(checkTodoForm(this));">
+<form name="f1" method="post" action="organizer.todo.php?action={if isset($task)}saveTask&id={$task.id}{else}createTask{/if}&sid={$sid}" onsubmit="return(checkTodoForm(this));">
 	<table class="listTable">
 		<tr>
-			<th class="listTableHead" colspan="2"> {if $task}{lng p="edittask"}{else}{lng p="addtask"}{/if}</th>
+			<th class="listTableHead" colspan="2"> {if isset($task)}{lng p="edittask"}{else}{lng p="addtask"}{/if}</th>
 		</tr>
 		<tr>
 			<td class="listTableLeft">* <label for="priority">{lng p="tasklist"}:</label></td>
 			<td class="listTableRight">
 				<select name="taskListID" id="taskListID">
 					{foreach from=$taskLists item=taskList}
-					<option value="{$taskList.tasklistid}"{if (!$task&&$taskListID==$taskList.tasklistid)||($task&&$task.tasklistid==$taskList.tasklistid)} selected="selected"{/if}>{text value=$taskList.title}</option>
+					<option value="{$taskList.tasklistid}"{if (!isset($task)&&$taskListID==$taskList.tasklistid)||(isset($task)&&$task.tasklistid==$taskList.tasklistid)} selected="selected"{/if}>{text value=$taskList.title}</option>
 					{/foreach}
 				</select>
 			</td>
@@ -30,21 +30,21 @@
 		<tr>
 			<td class="listTableLeft">{lng p="begin"}:</td>
 			<td class="listTableRight">
-				{html_select_date prefix="beginn" time=$task.beginn end_year="+5" start_year="-5" field_order="DMY" field_separator="."}, 
-				{html_select_time prefix="beginn" time=$task.beginn display_seconds=false}
+				{html_select_date prefix="beginn" time=$task.beginn|default:0 end_year="+5" start_year="-5" field_order="DMY" field_separator="."}, 
+				{html_select_time prefix="beginn" time=$task.beginn|default:0 display_seconds=false}
 			</td>
 		</tr>
 		<tr>
 			<td class="listTableLeft">{lng p="due"}:</td>
 			<td class="listTableRight">
-				{html_select_date prefix="faellig" time=$task.faellig end_year="+5" start_year="-5" field_order="DMY" field_separator="."}, 
-				{html_select_time prefix="faellig" time=$task.faellig display_seconds=false}
+				{html_select_date prefix="faellig" time=$task.faellig|default:0 end_year="+5" start_year="-5" field_order="DMY" field_separator="."}, 
+				{html_select_time prefix="faellig" time=$task.faellig|default:0 display_seconds=false}
 			</td>
 		</tr>
 		<tr>
 			<td class="listTableLeft">* <label for="erledigt">{lng p="done"}:</label></td>
 			<td class="listTableRight">
-				<input type="text" name="erledigt" id="erledigt" value="{if $task}{$task.erledigt}{else}0{/if}" size="5" /> %
+				<input type="text" name="erledigt" id="erledigt" value="{if isset($task)}{$task.erledigt}{else}0{/if}" size="5" /> %
 			</td>
 		</tr>
 		<tr>
@@ -62,9 +62,9 @@
 			<td class="listTableLeft"><label for="priority">{lng p="priority"}:</label></td>
 			<td class="listTableRight">
 				<select name="priority" id="priority">
-					<option value="1"{if $task && $task.priority==1} selected="selected"{/if}>{lng p="prio_1"}</option>
-					<option value="0"{if !$task || $task.priority==0} selected="selected"{/if}>{lng p="prio_0"}</option>
-					<option value="-1"{if $task && $task.priority==-1} selected="selected"{/if}>{lng p="prio_-1"}</option>
+					<option value="1"{if isset($task) && $task.priority==1} selected="selected"{/if}>{lng p="prio_1"}</option>
+					<option value="0"{if !isset($task) || $task.priority==0} selected="selected"{/if}>{lng p="prio_0"}</option>
+					<option value="-1"{if isset($task) && $task.priority==-1} selected="selected"{/if}>{lng p="prio_-1"}</option>
 				</select>
 			</td>
 		</tr>
@@ -83,4 +83,4 @@
 		</tr>
 	</table>
 </form>
-</div></div>
+</div></div>
\ No newline at end of file
diff --git a/src/templates/modern/li/organizer.todo.list.tpl b/src/templates/modern/li/organizer.todo.list.tpl
index 34172a5..f7d0af8 100644
--- a/src/templates/modern/li/organizer.todo.list.tpl
+++ b/src/templates/modern/li/organizer.todo.list.tpl
@@ -7,7 +7,7 @@
 		<th>
 			{lng p="title"}				
 		</th>
-		<th width="120">
+		<th width="140">
 			{lng p="due"}
 		</th>
 		<th width="100">
@@ -18,12 +18,12 @@
 	
 	<tr style="height:auto;">
 		<td colspan="6" class="folderGroup">
-			<a style="display:block;cursor:pointer;" onclick="toggleGroup(0,'todo0');">&nbsp;<img id="groupImage_0" src="{$tpldir}images/{if $smarty.cookies.toggleGroup.todo0=='closed'}expand{else}contract{/if}.png" width="11" height="11" border="0" align="absmiddle" alt="" />
+			<a style="display:block;cursor:pointer;" onclick="toggleGroup(0,'todo0');">&nbsp;<img id="groupImage_0" src="{$tpldir}images/{if isset($smarty.cookies.toggleGroup.todo0) && $smarty.cookies.toggleGroup.todo0=='closed'}expand{else}contract{/if}.png" width="11" height="11" border="0" align="absmiddle" alt="" />
 			&nbsp;{lng p="undonetasks"}</a>
 		</td>
 	</tr>
 	
-	<tbody id="group_0" style="display:{if $smarty.cookies.toggleGroup.todo0=='closed'}none{/if};">
+	<tbody id="group_0" style="display:{if isset($smarty.cookies.toggleGroup.todo0) && $smarty.cookies.toggleGroup.todo0=='closed'}none{/if};">
 
 	{foreach from=$todoList key=taskID item=task}{if $task.akt_status!=64}
 	{cycle values="listTableTD,listTableTD2" assign="class"}
@@ -67,7 +67,7 @@
 	
 	</tbody>
 	
-	{if $haveDoneTasks}
+	{if isset($haveDoneTasks)}
 	<tr style="height:auto;">
 		<td colspan="6" class="folderGroup">
 			<a style="display:block;cursor:pointer;" onclick="toggleGroup(1,'todo1');">&nbsp;<img id="groupImage_1" src="{$tpldir}images/{if $smarty.cookies.toggleGroup.todo1=='closed'}expand{else}contract{/if}.png" width="11" height="11" border="0" align="absmiddle" alt="" />
@@ -140,4 +140,4 @@
 	enableTodoDragTargets();
 	EBID('newTaskText').focus();
 //-->
-</script>
+</script>
\ No newline at end of file
diff --git a/src/templates/modern/li/prefs.signatures.edit.tpl b/src/templates/modern/li/prefs.signatures.edit.tpl
index 0bb1fc1..d5e3102 100644
--- a/src/templates/modern/li/prefs.signatures.edit.tpl
+++ b/src/templates/modern/li/prefs.signatures.edit.tpl
@@ -1,27 +1,27 @@
 <div id="contentHeader">
 	<div class="left">
 		<i class="fa fa-quote-right" aria-hidden="true"></i>
-		{if $signature}{lng p="editsignature"}{else}{lng p="addsignature"}{/if}
+		{if isset($signature)}{lng p="editsignature"}{else}{lng p="addsignature"}{/if}
 	</div>
 </div>
 
 <div class="scrollContainer"><div class="pad">
 
-<form name="f1" method="post" action="prefs.php?action=signatures&do={if $signature}saveSignature&id={$signature.id}{else}createSignature{/if}&sid={$sid}" onsubmit="{literal}if(checkSignatureForm(this)) { editor.submit(); return(true); } else return(false);{/literal}">
+<form name="f1" method="post" action="prefs.php?action=signatures&do={if isset($signature)}saveSignature&id={$signature.id}{else}createSignature{/if}&sid={$sid}" onsubmit="{literal}if(checkSignatureForm(this)) { editor.submit(); return(true); } else return(false);{/literal}">
 	<table class="listTable">
 		<tr>
-			<th class="listTableHead" colspan="2"> {if $signature}{lng p="editsignature"}{else}{lng p="addsignature"}{/if}</th>
+			<th class="listTableHead" colspan="2"> {if isset($signature)}{lng p="editsignature"}{else}{lng p="addsignature"}{/if}</th>
 		</tr>
 		<tr>
 			<td class="listTableLeft">* <label for="titel">{lng p="title"}:</label></td>
 			<td class="listTableRight">
-				<input type="text" name="titel" id="titel" value="{if isset($signature.titel)}{text value=$signature.titel allowEmpty=true}{/if}" style="width:100%;" />
+				<input type="text" name="titel" id="titel" value="{text value=$signature.titel|default:'' allowEmpty=true}" style="width:100%;" />
 			</td>
 		</tr>
 		<tr>
 			<td class="listTableLeft"><label for="text">{lng p="plaintext"}:</label></td>
 			<td class="listTableRight">
-				<textarea name="text" id="text" style="width:100%;height:150px;">{if isset($signature.text)}{text value=$signature.text allowEmpty=true}{/if}</textarea>
+				<textarea name="text" id="text" style="width:100%;height:150px;">{text value=$signature.text|default:'' allowEmpty=true}</textarea>
 			</td>
 		</tr>
 		<tr>
@@ -32,12 +32,10 @@
 					<script src="./clientlib/wysiwyg.js?{fileDateSig file="../../clientlib/wysiwyg.js"}"></script>
 					<script type="text/javascript" src="./clientlib/ckeditor/ckeditor.js?{fileDateSig file="../../clientlib/ckeditor/ckeditor.js"}"></script>
 					<script>
-					<!--
 						var editor = new htmlEditor('html', '{$tpldir}/images/editor/');
 						editor.init();
 						editor.switchMode('html', true);
 						registerLoadAction('editor.start()');
-					//-->
 					</script>
 				</div>
 			</td>
@@ -52,4 +50,4 @@
 	</table>
 </form>
 
-</div></div>
+</div></div>
\ No newline at end of file
diff --git a/src/templates/modern/li/search.details.tpl b/src/templates/modern/li/search.details.tpl
index 5b5aa50..5c488f1 100644
--- a/src/templates/modern/li/search.details.tpl
+++ b/src/templates/modern/li/search.details.tpl
@@ -22,20 +22,20 @@
 	<tr>
 		<th colspan="2">&nbsp;</th>
 		<th><a href="#" onclick="changeSearchSort('title','{$sortOrderInv}');">{lng p="title"}</a>
-			{if $sortColumn=='title'}<i class="fa {$sortOrder}" aria-hidden="true"></i>{/if}</th>
+			{if isset($sortColumn) && $sortColumn=='title'}<i class="fa {$sortOrder}" aria-hidden="true"></i>{/if}</th>
 		<th><a href="#" onclick="changeSearchSort('date','{$sortOrderInv}');">{lng p="date"}</a>
-			{if $sortColumn=='date'}<i class="fa {$sortOrder}" aria-hidden="true"></i>{/if}</th>
+			{if isset($sortColumn) && $sortColumn=='date'}<i class="fa {$sortOrder}" aria-hidden="true"></i>{/if}</th>
 		<th><a href="#" onclick="changeSearchSort('size','{$sortOrderInv}');">{lng p="size"}</a>
-			{if $sortColumn=='size'}<i class="fa {$sortOrder}" aria-hidden="true"></i>{/if}</th>
+			{if isset($sortColumn) && $sortColumn=='size'}<i class="fa {$sortOrder}" aria-hidden="true"></i>{/if}</th>
 		<th><a href="#" onclick="changeSearchSort('score','{$sortOrderInv}');">{lng p="relevance"}</a>
-			{if $sortColumn=='score'}<i class="fa {$sortOrder}" aria-hidden="true"></i>{/if}</th>
+			{if isset($sortColumn) && $sortColumn=='score'}<i class="fa {$sortOrder}" aria-hidden="true"></i>{/if}</th>
 	</tr>
 	
-	{if $results}
+	{if isset($results)}
 	{foreach from=$results item=resultCat key=resultCatID}
 	<tr>
 		<td width="24" align="center" class="folderGroup">
-			<input type="checkbox"{if !$resultCat.massActions} disabled="disabled"{else} onclick="checkAll(this.checked, document.forms.f1, 'checkbox_{$resultCatID}_');toggleResultMassActions(document.forms.f1, {$resultCatID});"{/if} />
+			<input type="checkbox"{if !isset($resultCat.massActions) || !$resultCat.massActions} disabled="disabled"{else} onclick="checkAll(this.checked, document.forms.f1, 'checkbox_{$resultCatID}_');toggleResultMassActions(document.forms.f1, {$resultCatID});"{/if} />
 		</td>
 		<td colspan="5" class="folderGroup">
 			<a style="display:block;" href="javascript:toggleGroup({$resultCatID});">&nbsp;<img id="groupImage_{$resultCatID}" src="{$tpldir}images/contract.png" width="11" height="11" border="0" align="absmiddle" alt="" />
@@ -47,7 +47,7 @@
 	{cycle values="listTableTR,listTableTR2" assign="class"}
 	<tr class="{$class}">
 		<td width="24" align="center">
-			<input type="checkbox" name="items[{$resultCat.name}][]" id="checkbox_{$resultCatID}_{$resultID}" value="{$result.id}"{if !$resultCat.massActions} disabled="disabled"{/if} onchange="toggleResultMassActions(document.forms.f1, {$resultCatID});" />
+			<input type="checkbox" name="items[{$resultCat.name}][]" id="checkbox_{$resultCatID}_{$resultID}" value="{$result.id|default:''}"{if !isset($resultCat.massActions) || !$resultCat.massActions} disabled="disabled"{/if} onchange="toggleResultMassActions(document.forms.f1, {$resultCatID});" />
 		</td>
 		<td width="24">
 			<i class="fa {if !empty($result.icon)}{$result.icon}{else}{$resultCat.icon}{/if}" aria-hidden="true"></i>
@@ -65,7 +65,7 @@
 		<td style="text-align:center;">{if !empty($result.score)}{$result.score} %{else}-{/if}</td>
 	</tr>
 	{/foreach}
-	{if $resultCat.massActions}
+	{if isset($resultCat.massActions) && $resultCat.massActions}
 	
 	<tr style="display:none;" id="massActions_{$resultCatID}">
 		<td colspan="6" class="listTableFoot" style="border-bottom:3px double #CCC;">
diff --git a/src/templates/modern/li/webdisk.folder.tpl b/src/templates/modern/li/webdisk.folder.tpl
index fcd41bb..825a592 100644
--- a/src/templates/modern/li/webdisk.folder.tpl
+++ b/src/templates/modern/li/webdisk.folder.tpl
@@ -25,7 +25,7 @@
 	<input type="hidden" name="selectedWebdiskItems" id="selectedWebdiskItems" value="" />
 	
 	<div class="scrollContainer withBottomBar noSelect" id="wdDnDArea">
-	{if $upload}
+	{if isset($upload)}
 		<fieldset style="margin-top:1em;">
 			<legend>{lng p="uploadfiles"}</legend>
 			<table width="100%">
@@ -119,21 +119,20 @@
 	
 	{hook id="webdisk.folder.tpl:foot"}
 	
-	{if !$smarty.post.inline}
+	{if !isset($smarty.post.inline)}
 	<script src="./clientlib/dndupload.js?{fileDateSig file="../../clientlib/dndupload.js"}" type="text/javascript"></script>
 	
 	<script>
-	<!--
 	{if $hotkeys}
 		registerLoadAction('registerWebdiskFolderHotkeyHandler()');
 	{/if}
 		initDnDUpload(EBID('mainContent'), 'webdisk.php?sid='+currentSID+'&folder={$folderID}&action=dndUpload', function() {literal}{{/literal} document.location.href='webdisk.php?sid='+currentSID+'&folder={$folderID}'; {literal}}{/literal});
 		currentWebdiskFolderID = {$folderID};
 		var treeID = webdiskGetTreeIDbyFolderID({$folderID});
-		if(treeID > 0)
+		if(treeID > 0) {
 			webdisk_d.openTo(treeID);
+		}
 		initWDSel();
-	//-->
 	</script>
 	{/if}
 
@@ -143,4 +142,4 @@
 
 <div id="rightSidebar">
 	{include file="li/webdisk.sidebar.tpl"}
-</div>
+</div>
\ No newline at end of file