When AjaxFileUpload post back it takes your page URL and appends onto the end of it it's own query strings (contextkey and guid). This works fine if your page URL doesn't already contain any query strings but if it does then you end up with a URL that contains two question marks which then corrupts your own final query string value and this in turn stops the upload from working.
Comments: I've figured out a workaround for me for now. I'm setting the variables in the query string to session variables then reloading the page without a query string. Works for me but would still appreciate a real solution.
Comments: I've figured out a workaround for me for now. I'm setting the variables in the query string to session variables then reloading the page without a query string. Works for me but would still appreciate a real solution.