Evaluation requires a thread to run temporarily. Use the Watch window to perform the evaluation

c# exception-handling thread-exceptions metatrader4
abatishchev picture abatishchev · Nov 25, 2010 · Viewed 19.4k times · Source

I'm completely stuck. I'm testing MetaTrader API and getting next error when tries to run a method in the Immediate Window of VS 2010:

A first chance exception of type 'System.Threading.ThreadAbortException' occurred in mscorlib.dll

A first chance exception of type 'System.Threading.ThreadAbortException' occurred in System.Runtime.Remoting.dll

Evaluation requires a thread to run temporarily. Use the Watch window to perform the evaluation.

What does it mean? Can it happens because of runtime versions difference (api 2.0, app 4.0)?

Answer

Omer Raviv picture Omer Raviv · Dec 8, 2013

I believe the method you are calling through the Immediate Window ends up calling Debugger.NotifyOfCrossThreadDependency. This method was only introduced in .NET 4.0, so it makes sense that the problem won't reproduce itself when using an older version of the runtime. This blog post explains NotifyOfCrossThreadDependency in detail, but the gist of it is that it causes the Watch window to show a Refresh button which must be pressed before the evaluation occurs. If it is evaluated through the Immediate Window, though, you get the "Evaluation requires a thread to run temporarily. Use the Watch window to perform the evaluation" error.

Here's an example property that reproduces this error:

    public int CauseError
    {
        get 
        {                
            Debugger.NotifyOfCrossThreadDependency();
            return 5;
        }
    }

Related questions

Get connection string from App.config

var connection = ConnectionFactory.GetConnection( ConfigurationManager.ConnectionStrings["Test"] .ConnectionString, DataBaseProvider); And this is my App.config: <?xml version="1.0" encoding="utf-8" ?> <configuration> <connectionStrings> <add name="Test" connectionString="Data Source=.;Initial Catalog=OmidPayamak;Integrated Security=True" …

Read More
Catch multiple exceptions at once?

It is discouraged to simply catch System.Exception. Instead, only the "known" exceptions should be caught. Now, this sometimes leads to unneccessary repetitive code, for example: try { WebId = new Guid(queryString["web"]); } catch (FormatException) { WebId = Guid.Empty; } catch (OverflowException) { WebId = …

Read More
How using try catch for exception handling is best practice

while maintaining my colleague's code from even someone who claims to be a senior developer, I often see the following code: try { //do something } catch { //Do nothing } or sometimes they write logging information to log files like following try catch …

Read More