yes, you are right, in 90% of the cases the errors are sitting in front of the keyboard
but in this case:
I have a XAMPP 3.2.2 with php 7 (settings see posting #9)
here I have the problems, when I install xoops 2.5.8
I have a XAMPP 3.2.1 with php 5.6
settings:
PHP Version 5.6.23
mySQL Version 5.6.16
Server API apache2handler
OS WINNT
table collation: utf8_general_ci
database server
Server: 127.0.0.1 via TCP/IP
Server type: MySQL
Server version: 5.6.16 - MySQL Community Server (GPL)
Protocol version: 10
User: root@localhost
Server charset: UTF-8 Unicode (utf8)
Server connection collation: utf8mb4_general_ci
if I install xoops 2.5.7.1 on XAMPP 3.2.1 I have no problems
The settings in phpMyAdmin seems to be the same, and it is not possible to switch Server connection collation from utf8mb4_general_ci to utf8_general_ci (if I select this, it always switching back, I don't know why)
therefore, blame on someone
and now