Question

I recently learned that the UpdatePanel uses HTTP requests with the “no-cache” header added. This causes images inside it to be downloaded on every UpdatePanel update. I do not want this.

So how do I prevent this?

I’ve thought about extending the UpdatePanel control and try scraping out the “no-cache”-part of the requests, but surely there must be a more elegant solution.

Answer 1

The UpdatePanel will only put the no-cache header on its own request for the update, not on requests to other resources like images. Those are handled by the browser like regular requests, even if they’re inside the UpdatePanel content.
Perhaps you simply forgot to put an Expires header on your image?