I think the more important mistake might be using ASP.NET AJAX. Check out more lightweight options like AJax.Net Pro, or just use Prototype or JQuery directly.

Well, ASP.NET Ajax is not just UpdatePanels. Instead I think it is a cool javascript library.

The fourth mistake, of course, is developing an ASP.NET AJAX application in the middle of a land war in Asia.

You're definitely right that UpdatePanels can easily be overused. In fact, one of the most popular posts on my blog is still "Why ASP.NET AJAX UpdatePanels are dangerous".

Regardless, there are very many developers out there using UpdatePanels, and running into these life cycle problems. Especially those starting fresh today, trying to learn it all at once. Hopefully, this post can find its way to a few of them before they make those mistakes.

Who knows. If they don't have to waste time trying to debug these issues, maybe they'll spend some of that time learning about page methods instead.

So the tip is to use ScriptManager.IsAsyncPostBack to check for postback?

Hopefully everyone doing ASP.NET work already knows about checking for Page.IsPostBack, so if the MS ASP.NET AJAX implementors are worth anything they should already have figured out to check for IsAsyncPostBack.

There's a bit more than IsAsyncPostBack there.

However, even that alone is something that many people are missing. Reading the ASP.NET forums' AJAX section for a bit makes that pretty obvious.

You have to remember that new developers are picking up ASP.NET for the first time every day. Those of us that are long-time ASP.NET developers benefited from being able to progressively learn from 1.0 to 2.0 to adding the AJAX extensions (and then forget it all when the MVC framework is released!). Competently jumping right into the thick of things today isn't a trivial task.