How to deny the usage of my product to a user?

Question

I am building an microcredit application that is checking for the user's eligibility.

Unfortunately not everyone is eligible, I have to announce it and it can generate some frustration. I would like to smoothen this experience as much as possible.

How can I write a message to inform the user that I cannot provide him access to my product and leave him on a rather positive note if possible?

Specifically:

• Should I apologize? (there is already a good response about apologizing for error messages here: https://ux.stackexchange.com/a/31362/112906)
• Should I try to explain the rationale behind? It can be quite complex and some part of the decision-making process cannot be communicated.
• Can I use visual elements or specific colors to improve this experience?
• Should I leave him with this last screen or propose some additional actions ? (eg a button to leave the app, propose him to leave some feedback, etc...)

Answer 1

Should I apologize?

No. You should maintain the feeling that the app is a neutral piece of technology, and the circumstances that led to the person being ineligible have nothing to do with the app. Some algorithm created a fact based on some factors, and that fact is being revealed. You should not be cruel or harsh with your tone when you explain this fact, but you should also not apologize.

Should I try to explain the rationale behind?

Yes. As much as is possible. This is your best opportunity to soften the blow. Even if it is just to explain that many complicated factors were used to make the decision. The worst thing is that the user feels like the decision was random or arbitrary.

You might consider sending unsuccessful applicants to a webpage that explains the process is slightly more detail (see last point, below)

Can I use visual elements or specific colors to improve this experience?

Again, this app is a neutral piece of technology, not a nurse or a babysitter. Design the screen that shows this message as you would any other screen. As soon as you start introducing additional visual elements, like images or color, you open the door for misinterpretation and a potential worsening of the situation.

Should I leave him with this last screen or propose some additional actions?

Only if there is a good reason to do so. Don't create UI that has to built, tested, and maintained just for the purpose of (maybe) making someone feel better. It should have some purpose.

e.g button to leave the app

This seems like a pratical addition, as the logical next step would be to leave the app.

propose him to leave some feedback

If you think there is enough potential value in this to justify the cost of dealing with the feedback you recieve, then sure, add it. Otherwise no.

Explanation Page

You say that the exact nature of the selection process can't be explained, but there must be something you describe. Sending a user to a screen that explains the process in as much detail as possible, and specifically informing them of those selection factors over which they have some control, would be a good way to end this experience.

Answer 2

We aim for delightful and pleasant experiences. Unfortunately, there are times where you have to deliver bad news to a user. There are a few things you can do to ease the sense of frustration and salvage the experience.

Priming

Mention in advance - so before the user sends off their application - that there is a chance their application won't go through. By priming them this way, you'll lessens the chance of disappointment when they fail, and perhaps even increase the satisfaction when they are eligible.

Always explain why something happened

Being rejected feels bad, but it's worse to not know why. Make sure you write this from an empathetic viewpoint, and omit jargon. Show understanding above all.
The user is disappointed and needs clear directions.

Find a positive angle or edge

Is there something they can do to fix the situation? If that's the case, offering encouragement and motivation to fix the situation can go a long way toward keeping your users. If there are any steps they can follow to become eligible, you can list them here. You can also show contact options in case the user has any questions. By showing support, you can still turn the negative situation into a positive experience.