I have a HTTPHandler that produces a Captcha image to the user whenever the

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Asked: May 12, 20262026-05-12T17:24:34+00:00 2026-05-12T17:24:34+00:00

I have a HTTPHandler that produces a Captcha image to the user whenever the

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I have a HTTPHandler that produces a Captcha image to the user whenever the captcha.ashx page is requested. The code for it is simple:

        CaptchaHandler handler = new CaptchaHandler();
        Random random = new Random();
        string[] fonts = new string[4] { "Arial", "Verdana", "Georgia", "Century Schoolbook" };
        string code = Guid.NewGuid().ToString().Substring(0, 5);
        context.Session.Add("Captcha", code);

        Bitmap imageFile = handler.GenerateImage(code, 100, 70, fonts[random.Next(0,4)]);
        MemoryStream ms = new MemoryStream();
        imageFile.Save(ms, System.Drawing.Imaging.ImageFormat.Png);

        byte[] buffer = ms.ToArray();

        context.Response.ClearContent();
        context.Response.ContentType = "image/png";
        context.Response.BinaryWrite(buffer);
        context.Response.Flush();

Then on my regular website, i got the following:

...
<img id="securityCode" src="captcha.ashx" alt="" /><br />
<a href="javascript:void(0);" onclick="javascript:refreshCode();">Refresh</a>
...

This works perfectly, the image is generated and sent back to the user whenever the captcha.ashx page is requested. My problem is that the HTTPHandler doesn’t save the session?
I tried to get the session back from the normal page but i only got an exception saying that it didn’t exist, so i turned on Trace to see what sessions that is active and it doesn’t list the session that the HTTPHandler created (Captcha).

The HTTPHandler uses IReadOnlySessionState to interact with the sessions. Does the HTTPHandler only have read-access and thus not storing the session?