So I did some reading of the related questions and had some interesting stuff but did not find my answer, at least did not understand the answer.
I am very new to AJ
I know this is an old post, but I just encounter this issue and found the answer in this thread. Hope it can help any one who encounter this.
I did not put any client side script in the code behind. I only put this code:
The code above need to be inside the body section and not the head section. I tried putting it before and after the script manager, or inside and outside of the UpdatePanel and found no issue with all options. So as long as this code is in the body section, it work for me.
Just make sure you change your defined datetimepicker class. For mine is "default-date-picker" in the js file.