Error 500 - Creating Matter

[Admin-LawfirmServices]

Hello.

Looking for some guidance with Error 500 when creating a new matter:

Error! Description Error occured in the system. Please contact the administrator Message List does not exist. The page you selected contains a list that does not exist. It may have been deleted by another user. ErrorCode 500 MethodName SetPermission ClassName SPList LineNumber 1269 StackTrace at Microsoft.SharePoint.Client.ClientRequest.ProcessResponseStream(Stream responseStream) at Microsoft.SharePoint.Client.ClientRequest.ProcessResponse() at Microsoft.Legal.MatterCenter.Repository.SPList.SetPermission(ClientContext clientContext, IList1 assignUserName, IList1 permissions, String listName) in C:\Matter_Center_4\tree\master\cloud\src\solution\Microsoft.Legal.MatterCenter.Service\Microsoft.Legal.MatterCenter.Repository\SharePointInfo\SPList.cs:line 1269 at Microsoft.Legal.MatterCenter.Web.Common.MatterProvision.AssignUserPermissions(MatterMetdataVM matterMetadataVM) in C:\Matter_Center_4\tree\master\cloud\src\solution\Microsoft.Legal.MatterCenter.Web\Common\MatterProvision.cs:line 803 at Microsoft.Legal.MatterCenter.Service.MatterController.AssignUserPermissions(MatterMetdataVM matterMetadataVM) in C:\Matter_Center_4\tree\master\cloud\src\solution\Microsoft.Legal.MatterCenter.Web\Controllers\MatterController.cs:line

Thanks.,