I am not sure what he is attempting to change it to - But I do not think it is something that minor.. When I find out I will inform here... 

When you say system won't let him - what exactly is going on? Does he get any error or message? 

What are the exact steps, usernames he uses? Keep us updated. 

He uses the name currently on the site as 'Aleph' and is attempting to add something to his name. This would be in the field that is the name displayed publicly on the site - 

When he inputs the information on profile edit, and attempts to save - there is no error, and nothing is saved. 

Lucifer, I will need the exact details to what he's trying to change his name and his access details to your website in order to check the issue as we cannot reproduce the issue on our side, besides you say everything is ok with your profile edit as well. 

That is not something I am at a liberty to divulge - however, is there certain characters that are not allowed on a display name change? For example, "~" or others? I am not sure what he attempting to change it into, however the only thing that I can think of is that there is a certain character or type of lettering that is not allowed by the Oxwall platform - 

IF and when I find out what he is attempting to change it to that may be an insight - I apologize if I am not being as forthcoming as would be helpful, however as per our site's privacy agreement some information cannot be given out. 

Lucifer, we'll need the exact steps and usernames he used in order to reproduce the issue. 

As to the username characters we support A-Z, a-z 0-9 and _ (underscore symbol)

This regexp is in ow_utilities/validator.php

line 36: const USER_NAME_PATTERN = '/^[\w]{1,32}$/';

 A word character is a character from a-z, A-Z, 0-9, including the _ (underscore) character.