diff --git a/library/Icinga/Web/Session/PhpSession.php b/library/Icinga/Web/Session/PhpSession.php
index 86d66b244..5df9e8744 100644
--- a/library/Icinga/Web/Session/PhpSession.php
+++ b/library/Icinga/Web/Session/PhpSession.php
@@ -138,6 +138,7 @@ class PhpSession extends Session
      */
     public function read()
     {
+        $this->clear();
         $this->open();
 
         foreach ($_SESSION as $key => $value) {
@@ -161,9 +162,15 @@ class PhpSession extends Session
     {
         $this->open();
 
+        foreach ($this->removed as $key) {
+            unset($_SESSION[$key]);
+        }
         foreach ($this->values as $key => $value) {
             $_SESSION[$key] = $value;
         }
+        foreach ($this->removedNamespaces as $identifier) {
+            unset($_SESSION[self::NAMESPACE_PREFIX . $identifier]);
+        }
         foreach ($this->namespaces as $identifier => $namespace) {
             $_SESSION[self::NAMESPACE_PREFIX . $identifier] = $namespace->getAll();
         }
diff --git a/library/Icinga/Web/Session/Session.php b/library/Icinga/Web/Session/Session.php
index 0717601ed..e81274e73 100644
--- a/library/Icinga/Web/Session/Session.php
+++ b/library/Icinga/Web/Session/Session.php
@@ -41,6 +41,13 @@ abstract class Session extends SessionNamespace
      */
     protected $namespaces = array();
 
+    /**
+     * The identifiers of all namespaces removed from this session
+     *
+     * @var array
+     */
+    protected $removedNamespaces = array();
+
     /**
      * Read all values from the underlying session implementation
      */
@@ -71,6 +78,10 @@ abstract class Session extends SessionNamespace
     public function getNamespace($identifier)
     {
         if (!isset($this->namespaces[$identifier])) {
+            if (in_array($identifier, $this->removedNamespaces)) {
+                unset($this->removedNamespaces[array_search($identifier, $this->removedNamespaces)]);
+            }
+
             $this->namespaces[$identifier] = new SessionNamespace();
         }
 
@@ -97,6 +108,7 @@ abstract class Session extends SessionNamespace
     public function removeNamespace($identifier)
     {
         unset($this->namespaces[$identifier]);
+        $this->removedNamespaces[] = $identifier;
     }
 
     /**
@@ -105,6 +117,8 @@ abstract class Session extends SessionNamespace
     public function clear()
     {
         $this->values = array();
+        $this->removed = array();
         $this->namespaces = array();
+        $this->removedNamespaces = array();
     }
 }
diff --git a/library/Icinga/Web/Session/SessionNamespace.php b/library/Icinga/Web/Session/SessionNamespace.php
index 9c49c3f63..4360e2828 100644
--- a/library/Icinga/Web/Session/SessionNamespace.php
+++ b/library/Icinga/Web/Session/SessionNamespace.php
@@ -45,6 +45,13 @@ class SessionNamespace implements IteratorAggregate
      */
     protected $values = array();
 
+    /**
+     * The names of all values removed from this container
+     *
+     * @var array
+     */
+    protected $removed = array();
+
     /**
      * Return an iterator for all values in this namespace
      *
@@ -52,7 +59,7 @@ class SessionNamespace implements IteratorAggregate
      */
     public function getIterator()
     {
-        return new ArrayIterator($this->values);
+        return new ArrayIterator($this->getAll());
     }
 
     /**
@@ -77,7 +84,7 @@ class SessionNamespace implements IteratorAggregate
     public function __get($key)
     {
         if (!array_key_exists($key, $this->values)) {
-            throw new Exception('Cannot access non-existent session value "' + $key + '"');
+            throw new Exception('Cannot access non-existent session value "' . $key . '"');
         }
 
         return $this->get($key);
@@ -101,6 +108,7 @@ class SessionNamespace implements IteratorAggregate
      */
     public function __unset($key)
     {
+        $this->removed[] = $key;
         unset($this->values[$key]);
     }
 
@@ -115,6 +123,11 @@ class SessionNamespace implements IteratorAggregate
     public function set($key, $value)
     {
         $this->values[$key] = $value;
+
+        if (in_array($key, $this->removed)) {
+            unset($this->removed[array_search($key, $this->values)]);
+        }
+
         return $this;
     }
 
@@ -150,10 +163,10 @@ class SessionNamespace implements IteratorAggregate
     public function setAll(array $values, $overwrite = false)
     {
         foreach ($values as $key => $value) {
-            if (isset($this->values[$key]) && !$overwrite) {
+            if ($this->get($key) !== $value && !$overwrite) {
                 continue;
             }
-            $this->values[$key] = $value;
+            $this->set($key, $value);
         }
     }
 }