After upgrade from EPIserver 5.0 R2 to 7.0, pagebrowser.aspx is not working and getting following error.

[EPiServerException: PageReference: Input string was not in a correct format.]
   EPiServer.Core.PageReference.Parse(String s) +77
   EPiServer.DataAccess.ContentDB.ReadPageReference(DbDataReader reader, PropertyData prop) +316
   EPiServer.DataAccess.ContentDB.ReadPropertyData(PropertyData prop, DbDataReader reader, ContentReference contentLink, CultureInfo language) +148
   EPiServer.DataAccess.ContentListDB.ReadPageList(DbCommand cmd) +1581
   EPiServer.DataAccess.<>c__DisplayClass19.b__18() +401
   EPiServer.Data.Providers.<>c__DisplayClass1`1.b__0() +57
   EPiServer.Data.Providers.SqlDeadlockRetryPolicy.Execute(Boolean isInTransaction, Func`1 method) +72
   EPiServer.Data.Providers.SqlDatabaseHandler.Execute(Func`1 action) +205
   EPiServer.DataAccess.ContentListDB.LoadSpecificContentInstances(Int32[] contentLinks, Int32 languageBranchID) +97
   EPiServer.DataAbstraction.ContentStore.LoadSpecificContentInstances(Int32[] contentLinks, Int32 languageBranchID) +31
   EPiServer.DefaultContentProvider.LoadContents(IList`1 contentReferences, ILanguageSelector selector) +339
   EPiServer.Core.ContentProvider.GetScatteredContents(IList`1 contentLinks, ILanguageSelector selector) +324
   EPiServer.Core.ContentProvider.LoadChildren(ContentReference contentLink, ILanguageSelector selector, Int32 startIndex, Int32 maxRows) +167
   EPiServer.<>c__DisplayClass3f.b__3e(ContentProvider provider) +106
   EPiServer.Core.ContentProviderMap.Iterate(Action`1 contentProviderHandler) +162
   EPiServer.DataFactory.GetWastebasketContent(ILanguageSelector selector, Int32 startIndex, Int32 maxRows) +125
   EPiServer.DataFactory.GetChildren(ContentReference contentLink, ILanguageSelector selector, Int32 startIndex, Int32 maxRows) +749
   EPiServer.DataFactory.GetChildren(ContentReference contentLink, ILanguageSelector selector) +60
   EPiServer.Web.WebControls.PageDataSource.GetChildrenForLoader(PageReference pageLink) +116
   EPiServer.Web.WebControls.HierarchicalPageLoader.GetFilteredChildren(PageReference pageLink) +45
   EPiServer.Web.WebControls.PageHierarchyData.EnsureChildrenLoaded() +36
   EPiServer.Web.WebControls.PageHierarchyData.get_HasChildren() +26
   EPiServer.UI.WebControls.PageTreeView.PopulateChildNodes(IHierarchicalEnumerable enumerable, Int32 depth, Int32 expandDepth, PageTreeNode parentNode, ArrayList populationPath) +530
   EPiServer.UI.WebControls.PageTreeView.PopulateChildNodes(IHierarchicalEnumerable enumerable, Int32 depth, Int32 expandDepth, PageTreeNode parentNode, ArrayList populationPath) +629
   EPiServer.UI.WebControls.PageTreeView.PopulateRecursive(String viewPath) +233
   EPiServer.UI.WebControls.PageTreeView.PerformDataBinding() +130
   System.Web.UI.WebControls.HierarchicalDataBoundControl.PerformSelect() +102
   System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +30
   EPiServer.UI.Edit.PageExplorer.OnLoad(EventArgs e) +554
   System.Web.UI.Control.LoadRecursive() +54
   System.Web.UI.Control.LoadRecursive() +145
   System.Web.UI.Control.LoadRecursive() +145
   System.Web.UI.Control.LoadRecursive() +145
   System.Web.UI.Control.LoadRecursive() +145
   System.Web.UI.Control.LoadRecursive() +145
   System.Web.UI.Control.LoadRecursive() +145
   System.Web.UI.Control.LoadRecursive() +145
   System.Web.UI.Control.LoadRecursive() +145
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +772