I've upgraded the site from 2.3.1 to 2.3.2. I ran /dev/build and flushed the url, but I still receive the following error when I click on the Files & Images tab. Any advice?

Sophie

[Notice] Undefined index: Folder_UnusedAssetsField
GET /admin/assets/
Line 157 in /home/content/s/j/b/sjbmaine/html/markwright/sapphire/core/ClassInfo.php

Source
148 	/**
149 	 * @todo Improve documentation
150 	 */
151 	static function ancestry($class, $onlyWithTables = false) {
152 		global $_ALL_CLASSES;
153 
154 		if(is_object($class)) $class = $class->class;
155 		else if(!is_string($class)) user_error("Bad class value " . var_export($class, true) . " passed to ClassInfo::ancestry()", E_USER_WARNING);
156 
157 		$items = $_ALL_CLASSES['parents'][$class];
158 		$items[$class] = $class;
159 		if($onlyWithTables) foreach($items as $item) {
160 			if(!DataObject::has_own_table($item)) unset($items[$item]);
161 		}
162 		return $items;
163 	}
Trace
•ClassInfo::ancestry(Folder_UnusedAssetsField) 
Line 451 of Object.php
•Object->__construct() 
Line 42 of CompositeField.php
•CompositeField->__construct(FieldSet) 
Line 429 of Folder.php
•Folder_UnusedAssetsField->__construct(Folder) 
Line 356 of Folder.php
•Folder->getCMSFields() 
Line 280 of AssetAdmin.php
•AssetAdmin->getEditForm(0) 
Line 925 of LeftAndMain.php
•LeftAndMain->EditForm() 

•call_user_func_array(Array,Array) 
Line 550 of ViewableData.php
•ViewableData->cachedCall(EditForm,,) 
Line 1002 of ViewableData.php
•ViewableData_Customised->cachedCall(EditForm,,) 
Line 591 of ViewableData.php
•ViewableData->hasValue(EditForm) 
Line 29 of .cache.home.content.s.j.b.sjbmaine.html.markwright.cms.templates.Includes.AssetAdmin_right.ss
•include(/tmp/silverstripe-cache-home-content-s-j-b-sjbmaine-html-markwright/.cache.home.content.s.j.b.sjbmaine.html.markwright.cms.templates.Includes.AssetAdmin_right.ss) 
Line 354 of SSViewer.php
•SSViewer->process(ViewableData_Customised) 
Line 773 of ViewableData.php
•ViewableData->renderWith(Array) 
Line 484 of LeftAndMain.php
•LeftAndMain->Right() 

•call_user_func_array(Array,Array) 
Line 408 of ViewableData.php
•ViewableData->XML_val(Right,,1) 
Line 983 of ViewableData.php
•ViewableData_Customised->XML_val(Right,,1) 
Line 71 of .cache.home.content.s.j.b.sjbmaine.html.markwright.cms.templates.LeftAndMain.ss
•include(/tmp/silverstripe-cache-home-content-s-j-b-sjbmaine-html-markwright/.cache.home.content.s.j.b.sjbmaine.html.markwright.cms.templates.LeftAndMain.ss) 
Line 354 of SSViewer.php
•SSViewer->process(ViewableData_Customised) 
Line 166 of Controller.php
•Controller->handleAction(HTTPRequest) 
Line 129 of RequestHandler.php
•RequestHandler->handleRequest(HTTPRequest) 
Line 122 of Controller.php
•Controller->handleRequest(HTTPRequest) 
Line 277 of Director.php
•Director::handleRequest(HTTPRequest,Session) 
Line 121 of Director.php
•Director::direct(/admin/assets/) 
Line 118 of main.php