cefsharp/CefSharp · error · InvalidOperationException

Could not execute method: {name}({parameters}) {optional: -

Error message

Could not execute method: {name}({parameters}) {optional: - Missing Parameters: {missingParams}}

What it means

Thrown by the synchronous TryCallMethod path when invoking the bound method (method.Function or its MethodInterceptor) raises any exception. The original exception is wrapped as the InnerException of the InvalidOperationException, and the message records the method name, the joined parameter list, and (if > 0) the count of missing parameters. This is effectively a re-throw with extra context.

Source

Thrown at CefSharp/Internals/JavascriptObjectRepository.cs:386

                        {
                            paramList.Add(Type.Missing);
                        }

                        parameters = paramList.ToArray();
                    }

                    if (obj.MethodInterceptor == null)
                    {
                        result = method.Function(obj.Value, parameters);
                    }
                    else
                    {
                        result = obj.MethodInterceptor.Intercept((p) => method.Function(obj.Value, p), parameters, method.ManagedName);
                    }
                }
                catch (Exception e)
                {
                    throw new InvalidOperationException("Could not execute method: " + name + "(" + String.Join(", ", parameters) + ") " + (missingParams > 0 ? "- Missing Parameters: " + missingParams : ""), e);
                }

                //For sync binding with methods that return a complex property we create a new JavascriptObject
                //TODO: Fix the memory leak, every call to a method that returns an object will create a new
                //JavascriptObject and they are never released
                if (!obj.IsAsync && result != null && IsComplexType(result.GetType()))
                {
                    var jsObject = CreateJavascriptObject(rootObject: false);
                    jsObject.Value = result;
                    jsObject.Name = "FunctionResult(" + name + ")";
                    jsObject.JavascriptName = jsObject.Name;

                    AnalyseObjectForBinding(jsObject, analyseMethods: false, analyseProperties: true, readPropertyValue: true);

                    result = jsObject;
                }

                return new TryCallMethodResult(true, result, exception); ;

View on GitHub (pinned to 16bc6e0711)

Solutions

1. Inspect the InnerException for the real root cause before the wrap.
2. Add null/argument validation at the start of the bound method and throw a clear domain exception.
3. Validate argument counts and types on the JS side before calling.
4. If using a MethodInterceptor, ensure it does not throw for valid calls.

Example fix

// before
public User GetUser(int id) => _users[id]; // IndexOutOfRange if invalid

// after
public User GetUser(int id)
{
    if (id < 0 || id >= _users.Count)
        throw new ArgumentException("id out of range: " + id, nameof(id));
    return _users[id];
}

// Validate argument count/types before calling if your interop layer exposes arity:
if (parameters == null || parameters.Length < requiredParamCount)
    throw new ArgumentException("Missing parameters for " + name);

try { result = repository.TryCallMethod(objectId, name, parameters, out result, out ex); }
catch (InvalidOperationException ex) when (ex.Message.StartsWith("Could not execute method"))
{ var root = ex.InnerException ?? ex; /* surface root cause to caller */ }

When it happens

Trigger: The bound C# method throws (NullReferenceException, ArgumentException, business error); parameter conversion/binding fails; the MethodInterceptor raises; too few arguments were supplied (missingParams > 0) causing a downstream failure.

Common situations: Method body hits a null ref; invalid arguments from JS; type conversion mismatches between JS values and .NET parameter types; interceptor enforcing a rule and rejecting the call.

Related errors

• Method {0} not found on Object of Type {1}
• name
• value
• To enable synchronous JS bindings set WcfEnabled true in Cef
• Object already bound with name:{name}

AI-assisted analysis of cefsharp/CefSharp@16bc6e0711 (2026-08-13). Data as JSON: /api/errors/e2da8a61649fb3d1. Report an issue: GitHub.