I have a page with an Update Panel, inside the update panel is a Placeholder control. This Placeholder is populated with a User Control dynamically. Partial Postbacks are raised either by a sub control of the User Control or by a button outside the Update
Panel. The button can change which User Control that populates the Placeholder. This button will also save data to the DB.
What our testers are doing is they have two browser windows/tabs open on the same page for the same record (they are testing for concurrency), in the one windows/tab they click the button and the user control within the placeholder changes a couple times.
When they go to the second tab and a Partial Postback is done, we sometimes following error occurs:
Failed to load viewstate. The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request. ...
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