DataError at /admin/myapp/mymodel/1/change/
(1366, "Incorrect string value: '\\xF0\\x9F\\x99...' for column 'text' at row 1")

nano /etc/mysql/mysql.conf.d/mysqld.cnf

#
# * Character Set
#
character_set_server = utf8mb4
collation_server = utf8mb4_unicode_ci

SELECT CONCAT('ALTER TABLE ', table_name, ' CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;') AS alter_statement
FROM information_schema.tables
WHERE table_schema = 'mydatabasename';

/etc/init.d/mysql restart

DATABASES = {
    "default": {
        "ENGINE": "django.db.backends.mysql",
        # ...
        "OPTIONS": {
            "charset": "utf8mb4",
        },
    },
}