On a fresh install, the setup process goes back to the step "1. Welcome!" just after step "5. Super User"

Expected Behavior

Just after submitting the form "5. Super User", we expect to go to the next step or an error.

Current Behavior

Just after submitting the form "5. Super User", the process goes to the step "1. Welcome!" without showing any error.

Possible Solution

I wrote the solution on this thread : https://forum.matomo.org/t/installer-starts-over-after-asking-super-user-details/39409

1 - Diagnostic

Just after SQL tables creation, I edited the file config/config.ini.php and added the following :

[log]
log_writers[] = "file"
log_level = "DEBUG"

Then, I follow the installation process until the input of super user logins/password form, and the error bringing us back to the initial step.

Then I've checked the logs :

ERROR Piwik\FrontController[2021-03-21 12:23:39 UTC] [41909] Uncaught exception: Error: Call to undefined function Piwik\filter_var() in /usr/local/www/XXXXX/stats/core/Piwik.php:683

2 - Solution

Install missing package :

pkg install php80-filter
service php-fpm restart

Everything ran as expected then.
The missing package should be mentionned at the step "2. System Check"

Steps to Reproduce (for Bugs)

1. Running the installation process on a system with :
   OS :
   FreeBSD 11.4-RELEASE-p8 amd64
   PHP :
   php80-8.0.3 PHP Scripting Language
   php80-curl-8.0.3 The curl shared extension for php
   php80-dom-8.0.3 The dom shared extension for php
   php80-filter-8.0.3 The filter shared extension for php
   php80-gd-8.0.3 The gd shared extension for php
   php80-iconv-8.0.3 The iconv shared extension for php
   php80-mbstring-8.0.3 The mbstring shared extension for php
   php80-openssl-8.0.3 The openssl shared extension for php
   php80-pdo-8.0.3 The pdo shared extension for php
   php80-pdo_mysql-8.0.3 The pdo_mysql shared extension for php
   php80-session-8.0.3 The session shared extension for php
   php80-simplexml-8.0.3 The simplexml shared extension for php
   php80-xml-8.0.3 The xml shared extension for php
   php80-zlib-8.0.3 The zlib shared extension for php

2. You can see that:

• "2. System Check" is OK
• You will be in a loop, going to step "1. Welcome!" just after step "5. Super User"

Context

Bug while running the installation process in a fresh system.

Your Environment

• Matomo Version: 4.2.1
• PHP Version: 8.0
  php80-8.0.3 PHP Scripting Language
  php80-curl-8.0.3 The curl shared extension for php
  php80-dom-8.0.3 The dom shared extension for php
  php80-filter-8.0.3 The filter shared extension for php
  php80-gd-8.0.3 The gd shared extension for php
  php80-iconv-8.0.3 The iconv shared extension for php
  php80-mbstring-8.0.3 The mbstring shared extension for php
  php80-openssl-8.0.3 The openssl shared extension for php
  php80-pdo-8.0.3 The pdo shared extension for php
  php80-pdo_mysql-8.0.3 The pdo_mysql shared extension for php
  php80-session-8.0.3 The session shared extension for php
  php80-simplexml-8.0.3 The simplexml shared extension for php
  php80-xml-8.0.3 The xml shared extension for php
  php80-zlib-8.0.3 The zlib shared extension for php
• Server Operating System: FreeBSD 11