I have a ultrawebgrid inside a updatepanel and after a asyncpostback the grid become not editable....
Is the grid's AJAX functionality enabled? If so, then this is likely expected. The AJAX functionality of WebGrid is not compatible with ASP.NET AJAX Extensions controls, including UpdatePanel. Your options are to replace the UpdatePanel with a WebAsyncRefreshPanel, or to deactivate the grid's AJAX functionality.
If the grid's AJAX functionality is not enabled, or if you disable it and the issue still occurs, then something else is happening. In this situation, I suggest that you submit a support request so that a Developer Support Engineer can investigate this more in-depth. The best thing you can do to expedite our handling this support request is to provide a sample project that we can run and debug that reproduces this behavior, since we'll know we're running the same code you are.
Where can I disable the grid ajax funtionality?
I use the ajax updatepanel because i need to force a asyncpostback by code from the server side,
i think this is not posible using the WebAsyncRefreshPanel.