If you have issues with the migration process, delete your browsing history and internet files. If you continue to have issues, try using Google Chrome to migrate to ALTS.
Instructions on clearing your cache and deleting internet files
For Internet Explorer:
Click on the gear wheel in the top right corner of the Internet Explorer web browser.
Click on Internet Options in the menu.
Click on delete to delete browsing history.
Select Temporary Internet files and website files and Cookies and website data.
Click on Delete.
On the bottom of the page the browser notifies you when the browser is cleared.
Click on Settings.
Click on View files.
Select all of the temporary internet files, press delete on your keyboard and select Yes to delete
the selected Cookies.
The files will be deleted. Click OK.
Step 11: Click on Apply, Then OK to exit.