ASP.NET Ajax UpdateProgress stopped working with ASP.NET 4.0

Recently I updated my asp.net 2.0 website to ASP.NET 4.0. After the upgrade, ASP.NET Ajax UpdateProgess on one of my page stopped working. After some web search, I found that I need to set the ClientIDMode for my postback control.

By default it is set to Inherit and I had to set it to ClientIDMode= “AutoID” and the UpdateProgress started working fine.

In other case I started getting the error:  get_PostBackElement is undefined

The above workaround resolved that error as well.

Hope this helps.