SharePoint - Sys.WebForms.PageRequestManagerServerErrorException: An unexpected error occured.

O evento descrito ocorreu na edição de uma pagina no SharePoint, conforme abaixo:

Evento no UI (User Interface):

"Sys.WebForms.PageRequestManagerServerErrorException: An unexpected error occured."

Evento nos logs do SharePoint:

w3wp.exe (0x182C) 0x2720 SharePoint Foundation Runtime tkau Unexpected System.UnauthorizedAccessException: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))    at Microsoft.SharePoint.Library.SPRequest.GetListsWithCallback(String bstrUrl, Guid foreignWebId, String bstrListInternalName, Int32 dwBaseType, Int32 dwBaseTypeAlt, Int32 dwServerTemplate, UInt32 dwGetListFlags, UInt32 dwListFilterFlags, Boolean bPrefetchMetaData, Boolean bSecurityTrimmed, Boolean bGetSecurityData, Boolean bPrefetchRelatedFields, ISP2DSafeArrayWriter p2DWriter, Int32& plRecycleBinCount)     at Microsoft.SharePoint.SPListCollection.EnsureListsData(Guid webId, String strListName)     at Microsoft.SharePoint.SPListCollection.Undirty()     at Microsoft.SharePoint.SPBaseCollection.GetEnumerator()     at Microsoft.SharePoint.SPWeb.GetCatalog(SPListTemplateType typeCatalog)     at Microsoft.SharePoint.Publishing.WebControls.MediaWebPart.get_WebPartAdderId()     at Microsoft.SharePoint.Publishing.WebControls.InsertMediaRibbonButton.RegisterRequiredScripts()     at Microsoft.SharePoint.Publishing.WebControls.InsertMediaRibbonButton.OnPreRender(EventArgs e)     at System.Web.UI.Control.PreRenderRecursiveInternal()     at System.Web.UI.Control.PreRenderRecursiveInternal()     at System.Web.UI.Control.PreRenderRecursiveInternal()     at System.Web.UI.Control.PreRenderRecursiveInternal()     at System.Web.UI.Control.PreRenderRecursiveInternal()     at System.Web.UI.Control.PreRenderRecursiveInternal()     at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) 

Solução / Causa:

Acima ocorre normalmente se os grupos default do SharePoint foram deletados / alterados. Nesse caso aqui "Leitores do Recurso de Estilo" que eu recriei. Você pode editar a pagina assim que você recriou o(s) grupo(s).

Grupos padrão do SharePoint no SharePoint Server

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