For the past couple of weeks, I've been fighting with a really strange error when using UpdatePanels on my websites. It seems that if a page stands idle for too long ("too long" is variable - sometimes it's a few seconds, other times it's minutes), I get a JavaScript popup with a PageRequestManagerParserErrorException message. Apparently the error only appears in FireFox!

The error message states something about it being caused by Response.Write(), HTTPHandlers or any other things that might change the output stream, thereby corrupting the AJAX request. I searched through my code and couldn't find any of the mentioned causes.

Now this morning, I decided to do a simple test. I've created an aspx page containing an UpdatePanel, a Timer and a Label. On the tick event of the timer, I just update the label with the current date and time. Simple and a "schoolbook" example of what AJAX can do.

When I run the page, the label starts updating. Now if I wait for long enough (again, variable), I get the exact same error message. So it turns out that it has nothing to do with page complexity, several UpdatePanels or anything like that. It's a general error.

After searching the web for likely solutions (or causes, so I could find my own solution), I've pretty much given up. Does anyone know what might be causing this error? I've attached my simple website so you can see what I've done. ANY feedback is greatly appreciated!

AJAXEnabledWebSite.zip (2.36 KB)
comments powered by Disqus