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Posted 2 Jan 2003


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Enable Debug.Assert under ASP.NET

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3.06/5 (9 votes)
22 Jan 2003
Enable Debug.Assert under ASP.NET just like under windows Forms

Sample Image - DebugListener.png


Class System.Diagnostics.Debug provides a serial of Debug methods, such as Debug.Assert, Debug.Fail. They only work under Windows.Form applications. Under ASP.NET, no popup window will show to alert user that debug version has caught a potential logic error!

Using the code

Edit your root web.config file of your ASP.NET project:

      <assert assertuienabled="false" logfilename="c:\Debug.log" />
         <trace autoflush="true" indentsize="0">
              <add type="AspNetDebugListener.DebugListener,AspNetDebugListener" />

How it works

TraceListener class provides the abstract base class for the listeners who monitor the trace and debug output. So derive a new class that can monitor debug output too.

public class DebugListener : TraceListener 
    public DebugListener() : this("Forks Asp.Net DebugTracer")

Filter the output string

DebugListener uses Environment.StackTrace to print out the stacktrace. But it will print out many useless Debug.Assert... calling frame, I use a filter to remove it:

string GetStatckTraceString()
    string s = Environment.StackTrace;
    StringBuilder sb = new StringBuilder(s.Length);
    using (StringReader reader = new StringReader(s))
        bool debugFound = false;
            string line = reader.ReadLine();
            if (line == null)

            if (line.IndexOf("System.Diagnostics.Debug.Assert") != -1)
                debugFound = true;

            if (debugFound)

    return sb.ToString();


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Comments and Discussions

GeneralMy vote of 2 Pin
amittrivedimca7-Jul-09 22:31
amittrivedimca7-Jul-09 22:31 
Generalhistory of Debug.Assert Pin
Michael Freidgeim23-Nov-11 11:13
Michael Freidgeim23-Nov-11 11:13 
Generalbreak into code when calling Debug.Assert Pin
Michael Freidgeim12-Aug-04 15:23
Michael Freidgeim12-Aug-04 15:23 
GeneralOther syntax Pin
Uwe Keim26-Jan-03 20:13
sitebuilderUwe Keim26-Jan-03 20:13 

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