Let's walk through the most common reasons why calling App.WorkWith().ListItems() throws exceptions in a WebService context, plus concrete fixes you can implement right away:

1. Missing Sitefinity Context Initialization #

When running code outside Sitefinity's standard request pipeline (like in a custom WebService), the platform's context often isn't properly initialized. This is the #1 culprit for these kinds of errors.

Fix: Add context initialization at the start of your WebService method:

// Basic initialization for single-site setups
Telerik.Sitefinity.Abstractions.SiteInitializer.Initialize();

// For multi-site environments, target a specific site
var targetSite = Telerik.Sitefinity.Multisite.SiteManager.GetManager().GetSite("your-site-url-name");
Telerik.Sitefinity.Abstractions.SiteInitializer.Initialize(targetSite);

2. Insufficient Permissions #

WebService requests run under a specific identity, which may lack permissions to access Live ListItems content.

Fix:
Either:

• Configure your WebService to run under a user account with Content View permissions for the target list.
  Or, temporarily elevate permissions using Sitefinity's security wrapper:

Telerik.Sitefinity.Security.SecurityManager.RunAs(() => 
{
    // Your ListItems query logic goes here
}, Telerik.Sitefinity.Security.UserManager.GetManager().GetAdminUser());

3. Invalid List Reference #

Your query uses o.Parent.UrlName == "listado-direcciones-formularios-venta"—if the list's UrlName is misspelled, case-mismatched, or the list no longer exists, this will fail.

Fix:
First, verify the list's exact UrlName in the Sitefinity backend (go to Content > Lists and check the list's properties). Then, make your query more reliable by fetching the list first:

var targetList = App.WorkWith().Lists()
    .Where(l => l.UrlName == "listado-direcciones-formularios-venta")
    .GetFirstOrDefault();

if (targetList == null)
{
    throw new InvalidOperationException("Target list 'listado-direcciones-formularios-venta' not found");
}

// Now use the list's ID for the query
var calles = App.WorkWith().ListItems()
    .Where(o => o.Parent.Id == targetList.Id && o.Status == ContentLifecycleStatus.Live)
    .Get()
    .OrderBy(o => o.Ordinal);

4. Lazy Loading Issues #

Accessing o.Parent directly in your Where clause can trigger lazy-loading errors, as Sitefinity's ORM may not be able to resolve the parent list in a non-pipeline context.

Fix: Eagerly load the parent list with the Include method:

var calles = App.WorkWith().ListItems()
    .Include(o => o.Parent)
    .Where(o => o.Parent.UrlName == "listado-direcciones-formularios-venta" && o.Status == ContentLifecycleStatus.Live)
    .Get()
    .OrderBy(o => o.Ordinal);

5. WebService Hosting Constraints #

If your WebService is a separate project (not hosted within the Sitefinity web app), it may lack access to Sitefinity's configuration and core assemblies.

Fix:

• Deploy your WebService within the Sitefinity web application to share the same app domain.
• If it must be a separate project, ensure all required Sitefinity assemblies are referenced, and your web.config includes Sitefinity's configuration sections.

Final Encapsulated WebService Method Example #

Here’s how your method should look with these fixes applied:

[WebMethod]
public List<SimpleTO> GetDirecciones()
{
    var direcciones = new List<SimpleTO>();
    
    // Initialize Sitefinity context
    Telerik.Sitefinity.Abstractions.SiteInitializer.Initialize();
    
    try
    {
        // Locate the target list
        var targetList = App.WorkWith().Lists()
            .Where(l => l.UrlName == "listado-direcciones-formularios-venta")
            .GetFirstOrDefault();
            
        if (targetList == null)
        {
            throw new InvalidOperationException("Listado de direcciones no encontrado");
        }
        
        // Run with elevated permissions to access Live content
        Telerik.Sitefinity.Security.SecurityManager.RunAs(() => 
        {
            var calles = App.WorkWith().ListItems()
                .Where(o => o.Parent.Id == targetList.Id && o.Status == ContentLifecycleStatus.Live)
                .Get()
                .OrderBy(o => o.Ordinal);
                
            foreach (var calle in calles)
            {
                var item = new SimpleTO();
                item.id = calle.Title.ToUpper();
                // Populate additional SimpleTO properties here
                direcciones.Add(item);
            }
        }, Telerik.Sitefinity.Security.UserManager.GetManager().GetAdminUser());
    }
    catch (Exception ex)
    {
        // Log the error for debugging (use Sitefinity's built-in logger)
        Telerik.Sitefinity.Services.SystemManager.GetLogger().Error("Error retrieving direcciones", ex);
        throw; // Or return a user-friendly error response
    }
    
    return direcciones;
}

Adjust the code to match your SimpleTO structure and any multi-site configurations you have in place.

内容的提问来源于stack exchange，提问作者Mauricio Gracia Gutierrez