unrecognizable characters when upgrade mysql use mysqldump

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unrecognizable characters when upgrade mysql use mysqldump


in the same host, we wan to upgrade from mysql 5.6 to mysql 5.7

the step is as belows:
1.
we create new dirctory to store new mysql 5.7 soft and data.

2.
we use mysqldump -db-charater=utf-8 * to export 5.6 data


3.1
in 5.7, create user and database
3.2
we use mysqldump -db-charater=utf-8 to import step 2 data to 5.7


4.we have double check the charter-set varibles in 5.6 and 5.7
they are all same ,is utf-8.



the issue is :
since our application did't change , only db have move from 5.6 to 5.7,
and the application (ie) show unrecognizable characters when display local language

is there any suggestion how to check the issue?