I am upgrading a very old site, and in general, things are going astonishingly well. Got the backend and most of the site working; the rest is custom code I need to modify myself with one exception; members.

The member lists work perfectly, and the Examine indexes all run, but when I click a member details, although it loads the member, I get an error:

System.InvalidOperationException: Multiple actions were found that match the request:   
GetByIds on type Umbraco.Web.Editors.EntityController  
GetByIds on type Umbraco.Web.Editors.EntityController  
GetByIds on type Umbraco.Web.Editors.EntityController

Stack trace:

at 
System.Web.Http.Controllers.ApiControllerActionSelector.ActionSelectorCacheItem.SelectAction(HttpControllerContext controllerContext) at 
System.Web.Http.Controllers.ApiControllerActionSelector.SelectAction(HttpControllerContext controllerContext)    at 
Umbraco.Web.Editors.ParameterSwapControllerActionSelector.SelectAction(HttpControllerContext controllerContext)    at 
System.Web.Http.ApiController.ExecuteAsync(HttpControllerContext controllerContext, CancellationToken cancellationToken)    at 
System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()

Any ideas?