Upgrading MySQL 5.7 to 8.x on Windows Datadir path ignored

[Thomas Behrens]

I tried a lot but without success. I'm using MySQL 5.7 installed in Default dir C:\ I moved the datadirectory to drive D:\Programme\MySQL\Data
Everyting fine with 5.7

After upgrading to 8.0 I cannot start.
- I tried MySQL Installer
- I tried replace the bin dir.
- I tried 3 days with several hints from the web

[System] [MY-010116] [Server] C:\Program Files\MySQL\MySQL Server 5.7\bin\mysqld.exe (mysqld 8.0.20) starting as process 17400
[Warning] [MY-010091] [Server] Can't create test file C:\Program Files\MySQL\MySQL Server 5.7\data\mysqld_tmp_file_case_insensitive_test.lower-test
[Warning] [MY-010091] [Server] Can't create test file C:\Program Files\MySQL\MySQL Server 5.7\data\mysqld_tmp_file_case_insensitive_test.lower-test
[ERROR] [MY-013276] [Server] Failed to set datadir to 'C:\Program Files\MySQL\MySQL Server 5.7\data\' (OS errno: 2 - No such file or directory)

Of course directory "C:\Program Files\MySQL\MySQL Server 5.7\data\" is not existing. In my my.ini I have the datadir Option datadir="D:/Programme/MySQL/Data"
But this option is ignored.

Thanks for you help
Thomas