A customer following error message was shown to me, When I tried the database have symfony to create:
General error: 1709 Index column size too large. The maximum column size is 767 bytes.
This is because, the Strato strange setting in their managed hosting packages such as z.B. has the STRATO PowerWeb. Strato unfortunately won't change this setting, but you can in symfony in the doctrine.yaml (config.YAML) change the charset, Symfony works well on a Strato Server:
doctrine: dbal: # configure these for your database server driver: 'pdo_mysql' server_version: '5.6' charset: utf8 default_table_options: charset: utf8 collate: utf8_general_ci