Unhandled exception when trying to register a duplicate username with equality mismatch between php and database layer

This was solved for case sensitivity by adding the function caseInsensitiveArrayIntersect(). Maybe that should be replaced/updated with a function that instead uses something like iconv() as suggested here https://stackoverflow.com/questions/471021/comparing-strings-in-php-the-...

Changes are made on on 11.x (our main development branch) first, and are then back ported as needed according to our policies.

The issue seems the same as 🐛 Able to create user accounts with the same email address Active . On the issue, it was trying to handle the case insensitively with mb_strtoupper(). But am unable to match the words example and éxample.

Below is the observation received on ISO-8859-1//TRANSLIT as per https://stackoverflow.com/questions/471021/comparing-strings-in-php-the-...

echo iconv('UTF-8', 'ISO-8859-1//TRANSLIT', 'éxample'); // Output is �xample

I tried this ASCII//TRANSLIT is working as fine. As per, https://stackoverflow.com/questions/24504331/how-to-compare-two-strings-...
echo iconv('UTF-8', 'ASCII//TRANSLIT', 'éxample'); // Output is example

Creating as MR as per the above suggestion. Feel free to update the MR.

It sounds like this was probably fixed in the latest Drupal core update, although the vulnerability is only detailed for email addresses, not usernames. https://www.drupal.org/sa-core-2024-004 →

@caesius
Hope the issue with the page break. Still, the issue persists after the https://www.drupal.org/sa-core-2024-004 → patch moved. I can replicate it today also on the latest pull.

Hope the issue persists, to handle the exception.

Issue summary is missing template sections.

left other comments on MR.

As per the #12 comment updated the Issue summary and addressed the changes requested in MR. The pipeline has passed and is moving to NR.

All the open threads still apply so leaving in review.