Since upgrading from 7.5.9 i have been getting these errors on this line,

var result2 = await UserManager.AddLoginAsync(user.Id, loginInfo.Login);

System.NullReferenceException: Object reference not set to an instance of an object.
   at Umbraco.Core.Persistence.Database.BeginTransaction(IsolationLevel isolationLevel)
   at UmbracoIdentity.ExternalLoginStore.SaveUserLogins(Int32 memberId, IEnumerable`1 logins) in X:\Projects\Umbraco\UmbracoIdentity\src\UmbracoIdentity\ExternalLoginStore.cs:line 177
   at UmbracoIdentity.UmbracoMembersUserStore`1.<UpdateAsync>d__12.MoveNext() in X:\Projects\Umbraco\UmbracoIdentity\src\UmbracoIdentity\UmbracoMembersUserStore.cs:line 162
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNet.Identity.UserManager`2.<UpdateAsync>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNet.Identity.UserManager`2.<AddLoginAsync>d__61.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at U726.Controllers.UmbracoIdentityAccountController.<ExternalLoginCallback>d__13.MoveNext() in