Extender/Script controls may not be registered before PreRender

If you receive an error similar to this, it’s time to look for a missing call to base.OnPreRender.

If you override OnPreRender(EventArgs e) in a custom control, the conventional wisdom says you need to remember to call base.OnPreRender(e). Recently, I ran into this issue and found out the hard way that the page which hosts your control also must call base.OnPreRender in its OnPreRender (if you override it at all).

I hope I saved someone an hour or two of debugging. Thanks to Daniel Balla for pointing me in the right direction.

Yes you did -- Thanks a lot....

Thanks you did save me an hour or two

Thanks. You did indeed save me some time.

I'll add to the comments here... yes, that did save a lot of time and a lot of head-desk action...

Thanks!

Cool.. thanks.

Thank you for posting this.

Could you help me ? I make a custom control which have a ScriptManager and a CalendarExtender .They were defined in the CreateChildControls.I didnot override OnPreRender. But I still had this
error(Extender controls may not be registered before PreRender.).
What's wrong?
I am sorry.I am a chinese.My english is bad.
Thanks.

sunfly,
have you managed to fix your problem?
I have the same problem and need a solution.

Hi Milan,
I didnt override the prerender event but i do get the same error, can u guess the source of error,
I am using Calendar Extender Control in .ascx & while implementing this in a sharepoint site i get this error.

thanks ,
Surya

Unfortunately, I can't guess the source of error. Perhaps, overriding OnPreRender would be a good idea. :)

Milan,
Thanks, I did tried your suggestion, thing is that i am not using Prerender event in my Usercontrols altogether. So there might be something i have left out.. Will try & find the cause & Share things with you.

Also it works fine in Few usercontrols & shows up such error in other user controls

thanks for ur time...

Surya

Thanks to you and Daniel Balla ;)

Thanks Milan,
My user control started showing this error when I moved it onto an UpdatePanel. I got it working after I removed a 'using statement' referencing 'Page' during the 'OnLoad()' event, e.g.:

protected override void OnLoad(EventArgs e)
{
    base.OnLoad(e);
    Page parentPage = this.Page as Page;
    using (parentPage)
    {
    }
}

The using statement wasn't a good idea in the first place but I'd like to know what it was doing to page to cause the error.

Sean.

Yep, you saved me quite the headache! Thank you!

Yes, you saved me alot of debug time! Thanks!