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[Gordan Bobic <gordan.bobic@xxxxxxxxx>]

On this page:
https://mariadb.com/kb/en/json-data-type/

it states:
If you must use row-based replication and cannot change the MySQL
master from JSON to TEXT, you can try to introduce an intermediate
MySQL slave and change the column type from JSON to TEXT on it. Then
you replicate from this intermediate slave to MariaDB.

I can confirm that this does not work with MySQL 5.7. If you have a
5.7 master and you replicate to 5.7 slave, and you convert the slave's
json columns to longtext, replication fails with this error:

"Column X of table 'dbname.tablename' cannot be converted from type
'json' to type 'longtext'"

Using longblob doesn't work either.

So it seems there is currently no viable solution for replicating
anything that involves JSON columns from MySQL to MariaDB.