Yesterday I updated one of our sites from 7.6.3 to 7.7.6. and now I can't access anything other than content.

The sidebar in umbraco is empty and I keep getting a 500 response on two calls for GetSections() which are caused by a null reference exception on Sectioncontroller.

I have found similar issues here and here but the solutions don't seem to be working for me.

I have compared my application, trees and web config files with one of our sites that is currently running on 7.7.6 but couldn't find any differences that would cause this.

The application.config looks like this:

<?xml version="1.0" encoding="utf-8"?>
<applications>
  <add alias="content" name="Content" icon="traycontent" sortOrder="0" />
  <add alias="media" name="Media" icon="traymedia" sortOrder="1" />
  <add alias="settings" name="Settings" icon="traysettings" sortOrder="2" />
  <add alias="developer" name="Developer" icon="traydeveloper" sortOrder="3" />
  <add alias="users" name="Users" icon="trayuser" sortOrder="4" />
  <add alias="member" name="Members" icon="traymember" sortOrder="5" />
  <add alias="translation" name="Translation" icon="traytranslation" sortOrder="7" />
  <add alias="GCS" name="GCS" icon="icon-binoculars" sortOrder="20" />
</applications>

The trees.config looks like this:

<?xml version="1.0" encoding="utf-8"?>
<trees>
  <!--Content-->
  <add initialize="true" sortOrder="0" alias="content" application="content" title="Content" iconClosed="icon-folder" iconOpen="icon-folder" type="Umbraco.Web.Trees.ContentTreeController, umbraco" />
  <add initialize="false" sortOrder="0" alias="contentRecycleBin" application="content" title="Recycle Bin" iconClosed="icon-folder" iconOpen="icon-folder" type="umbraco.cms.presentation.Trees.ContentRecycleBin, umbraco" />

  <!--Media-->
  <add initialize="true" sortOrder="0" alias="media" application="media" title="Media" iconClosed="icon-folder" iconOpen="icon-folder" type="Umbraco.Web.Trees.MediaTreeController, umbraco" />
  <add initialize="false" sortOrder="0" alias="mediaRecycleBin" application="media" title="Recycle Bin" iconClosed="icon-folder" iconOpen="icon-folder" type="umbraco.cms.presentation.Trees.MediaRecycleBin, umbraco" />

  <!--Settings-->
  <add initialize="true" sortOrder="0" alias="documentTypes" application="settings" title="Document Types" iconClosed="icon-folder" iconOpen="icon-folder-open" type="Umbraco.Web.Trees.ContentTypeTreeController, umbraco" />
  <add application="settings" alias="templates" title="Templates" iconClosed="icon-folder" iconOpen="icon-folder-open" type="Umbraco.Web.Trees.TemplatesTreeController, umbraco" initialize="true" sortOrder="1" />
  <add application="settings" alias="partialViews" title="Partial Views" silent="false" initialize="true" iconClosed="icon-folder" iconOpen="icon-folder" type="Umbraco.Web.Trees.PartialViewsTreeController, umbraco" sortOrder="2" />
  <add application="settings" alias="stylesheets" title="Stylesheets" type="umbraco.loadStylesheets, umbraco" iconClosed="icon-folder" iconOpen="icon-folder" sortOrder="3" />
  <add application="settings" alias="stylesheetProperty" title="Stylesheet Property" type="umbraco.loadStylesheetProperty, umbraco" iconClosed="" iconOpen="" initialize="false" sortOrder="0" />
  <add application="settings" alias="scripts" title="Scripts" type="Umbraco.Web.Trees.ScriptTreeController, umbraco" iconClosed="icon-folder" iconOpen="icon-folder" sortOrder="4" />
  <add application="settings" alias="languages" title="Languages" iconClosed="icon-folder" iconOpen="icon-folder-open" type="Umbraco.Web.Trees.LanguageTreeController, umbraco" sortOrder="5" />
  <add initialize="true" sortOrder="7" alias="mediaTypes" application="settings" title="Media Types" iconClosed="icon-folder" iconOpen="icon-folder-open" type="Umbraco.Web.Trees.MediaTypeTreeController, umbraco" />

  <!--Developer-->
  <add initialize="true" sortOrder="0" alias="packager" application="developer" iconClosed="icon-folder" iconOpen="icon-folder-open" type="Umbraco.Web.Trees.PackagesTreeController, umbraco" />
  <add initialize="true" sortOrder="1" alias="dataTypes" application="developer" title="Data Types" iconClosed="icon-folder" iconOpen="icon-folder" type="Umbraco.Web.Trees.DataTypeTreeController, umbraco" />
  <add application="developer" alias="macros" title="Macros" type="umbraco.loadMacros, umbraco" iconClosed="icon-folder" iconOpen="icon-folder" sortOrder="2" />
  <add application="developer" alias="relationTypes" title="Relation Types" type="umbraco.loadRelationTypes, umbraco" iconClosed="icon-folder" iconOpen="icon-folder" sortOrder="4" />
  <add application="developer" alias="xslt" title="XSLT Files" type="umbraco.loadXslt, umbraco" iconClosed="icon-folder" iconOpen="icon-folder" sortOrder="5" />
  <add application="developer" alias="partialViewMacros" type="Umbraco.Web.Trees.PartialViewMacrosTreeController, umbraco" silent="false" initialize="true" sortOrder="6" title="Partial View Macro Files" iconClosed="icon-folder" iconOpen="icon-folder" />

  <!--Users-->
  <add initialize="true" sortOrder="0" alias="users" application="users" iconClosed="icon-folder" iconOpen="icon-folder-open" type="Umbraco.Web.Trees.UserTreeController, umbraco" />

  <!--Members-->
  <add initialize="true" sortOrder="0" alias="member" application="member" title="Members" iconClosed="icon-folder" iconOpen="icon-folder-open" type="Umbraco.Web.Trees.MemberTreeController, umbraco" />
  <add initialize="true" sortOrder="1" alias="memberTypes" application="member" title="Member Types" iconClosed="icon-folder" iconOpen="icon-folder-open" type="Umbraco.Web.Trees.MemberTypeTreeController, umbraco" />
  <add application="member" sortOrder="2" alias="memberGroups" title="Member Groups" type="umbraco.loadMemberGroups, umbraco" iconClosed="icon-folder" iconOpen="icon-folder" />

  <!--Translation-->
  <add application="translation" alias="dictionary" title="Dictionary" type="umbraco.loadDictionary, umbraco" iconClosed="icon-folder" iconOpen="icon-folder" sortOrder="0" />
  <add silent="false" initialize="true" sortOrder="1" alias="openTasks" application="translation" title="Tasks assigned to you" iconClosed="icon-folder" iconOpen="icon-folder" type="umbraco.loadOpenTasks, umbraco" />
  <add silent="false" initialize="true" sortOrder="2" alias="yourTasks" application="translation" title="Tasks created by you" iconClosed="icon-folder" iconOpen="icon-folder" type="umbraco.loadYourTasks, umbraco" />

  <!-- Custom -->
  <!--<add application="myApplication" alias="myTree" title="Me Tree" type="MyNamespace.myTree, MyAssembly"
       iconClosed="icon-folder" iconOpen="icon-folder" sortOrder="10" />-->
  <add initialize="true" sortOrder="8" alias="contentBlueprints" application="settings" iconClosed="icon-folder" iconOpen="icon-folder-open" type="Umbraco.Web.Trees.ContentBlueprintTreeController, umbraco" />
</trees>

Any ideas on how to fix this?