After Update Mysql 8.0.13 to 8.0.15 MySql Server Fails with error code = 1265

After Upgrading from MySql 8.0.13 (compiled from sourcecode) to MySql 8.0.15, the MySql Server can not start. Log: 2019-02-12T10:09:52.275336Z 1 [ERROR] [MY-013178] [Server] Execution of server-side SQL statement 'INSERT INTO routines SELECT * FROM mysql.routines' failed with error code = 1265, error message = 'Daten abgeschnitten für Feld 'sql_mode' in Zeile 7'. 2019-02-12T10:09:52.302630Z 0 [ERROR] [MY-010020] [Server] Data Dictionary initialization failed. 2019-02-12T10:09:52.302856Z 0 [ERROR] [MY-010119] [Server] Aborting "Daten abgeschnitten für Feld" means "Data truncated for field" - its a german version ... table checker does not find any errors - how can I solve this problem ? yours sincerely Robert