Error adding an app to site (add app from site menu)

When I'm trying to add app to any of my sites (I need to add a list) - on page ../addanapp.aspx I've got an error (like script error):

<?xml version="1.0" encoding="utf-8"?><soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><SendClientScriptErrorReport xmlns="http://schemas.microsoft.com/sharepoint/diagnostics/"><message>Sys.ArgumentNullException: Value cannot be null. Parameter name: element</message><file>ScriptResource.axd</file><line>4191</line><stack>&lt;stack&gt;&lt;function depth=&quot;0&quot; signature=&quot;Sys$UI$DomElement$addCssClass(element, className)&quot;&gt; &lt;![CDATA[function Sys$UI$DomElement$addCssClass(element, className) {      /// &lt;summary locid=&quot;M:J#Sys.UI.DomElement.addCssClass&quot; /&gt;      /// &lt;param name=&quot;element&quot; domElement=&quot;true&quot;&gt;&lt;/param&gt;      /// &lt;param name=&quot;className&quot; type=&quot;String&quot;&gt;&lt;/param&gt;     var e = Function._validateParams(arguments, [          {name: &quot;element&quot;, domElement: true},          {name: &quot;className&quot;, type: String}      ]);     if (e) throw e;      if (!Sys.UI.DomElement.containsCssClass(element, className)) {          if (element.className === &apos;&apos;) {              element.className = className;          }          else {              element.className += &apos; &apos; + className;          }      }  }]]&gt;&lt;/function&gt; &lt;function depth=&quot;1&quot; signature=&quot;SP_Storefront_ManagementView$get_$30_3()&quot;&gt;&lt;/function&gt; &lt;function depth=&quot;2&quot; signature=&quot;SP_Storefront_ManagementView$$4q_3()&quot;&gt;&lt;/function&gt;&lt;function depth=&quot;3&quot; signature=&quot;SP_Storefront_ManagementView()&quot;&gt;&lt;/function&gt; &lt;function depth=&quot;4&quot; signature=&quot;SP_Storefront_StorefrontApp$$4K($p0)&quot;&gt;&lt;/function&gt;&lt;function depth=&quot;5&quot;signature=&quot;SP_Storefront_StorefrontApp$$4G()&quot;&gt;&lt;/function&gt; &lt;function depth=&quot;6&quot; signature=&quot;SP_Storefront_StorefrontApp$updateUIAndState($

What's going on and how can I repair this?