I have an app where the user can choose to do multiple actions all at once. This is done by first choosing the actions, putting them in an "outbox" (like a cart in an online shop) and then executing them all at once by pressing the "Send"-button. Most of the time it works fine, but somethimes the whole, or part of the outbox fails. What is the best way to handle this?
Display an error message that lets the user know something went wrong, with the options to Cancel or Try again
Display a message stating what went right and what went wrong and then land the user back in the outbox so the user can make optional changes and try again.
Display a message stating what went right and what went wrong and then land the user on the startpage, with the actions not executed remaining "hidden" in the outbox (an icon with a number on it)
Or maybe a completely different approach?
If some of the actions succeed and some don't, is it best to show two messages (one for what went right and one for what went wrong) or one combined?
Generally we try to use the principles of Material design, but I haven't found a solution for this problem there.