When you are trying to work with " Import /Export "alarm functionality with IE 9 Browser,you may be facing the following the message in BizTalk 360 because IE9 doesn't support FileReader API. There is no official support in the DOM object, where as other browsers like chrome and Firefox get support.
Therefore you can't read the file in the browser. For the image upload we no need to read the file for further processing just upload functionality alone happen and as well many third party plugins are available to upload the image.
In our case we need to perform the file manipulations in browser itself. Hence we are not supporting the import and export in the IE9 browser.