TYPO3 Core

While upgrading TYPO3 8.6.1 to 8.7.0 using the upgrade wizard I just went into the following exception after the "Create tables and fields" action.

Oops, an error occurred!
An exception occurred while executing 'SELECT COUNT(*) FROM `sys_refindex` WHERE `hash` <> LOWER(MD5(CONCAT_WS('///', CAST(`tablename` AS CHAR), CAST(`recuid` AS CHAR), CAST(`field` AS CHAR), CAST(`flexpointer` AS CHAR), CAST(`softref_key` AS CHAR), CAST(`softref_id` AS CHAR), CAST(`deleted` AS CHAR), CAST(`workspace` AS CHAR), CAST(`ref_table` AS CHAR), CAST(`ref_uid` AS CHAR), CAST(`ref_string` AS CHAR), '2')))': Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (utf8_general_ci,COERCIBLE) for operation '<>'

The install Tool keeps crashing and throwing this exeption until I did the following fix to the Database:

mysql> SET collation_connection = 'utf8_general_ci';
mysql> USE your_typo3_database
mysql> ALTER DATABASE your_typo3_database CHARACTER SET utf8 COLLATE utf8_general_ci;
mysql> ALTER TABLE sys_refindex CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;

Originally the iInstance was installed on TYPO3 7.6 LTS and upgraded to 8.6.1 a couple of weeks ago without any problems. I did a rollback of the machine and tried the upgrade again and again doing all the Compare Database stuff etc. in different order before the upgrade to 8.7 always ending up in a crashed install Tool. However this might be a general problem under some circumstances. Having done the database changes there where no further problems upgrading to 8.7

System:
Debian 8
MySQL 5.5.52
PHP 7.0.17 fpm