clickhouse external dictionary loading error - clickhouse

Question

I plan to upgrade clickhouse cluster.From v19.14.6. to v21.3.10.But when I load a mysql external dictionary on v21.3.10,I got an error:
Query:
SYSTEM RELOAD DICTIONARY dim_subject_movie
Received exception from server:
Poco::Exception. Code: 1000, e.code() = 0, e.displayText() = Exception: Connections to all replicas failed: frodo#mysql1:3306 as user test, frodo#mysql1:3306 as user test (version 21.3.10.1 (official build))
The configuration are as follows
<dictionary>
<name>dim_subject_movie</name>
<source>
<mysql>
<port>3306</port>
<user>test</user>
<password>test1</password>
<replica>
<host>mysql1</host>
<priority>1</priority>
</replica>
<db>frodo</db>
<table>subject_movie_collection</table>
<where>date=subdate(current_date, 1)</where>
</mysql>
</source>
<lifetime>
<min>300</min>
<max>360</max>
</lifetime>
<layout><hashed /></layout>
<structure>
<id>
<name>movie_id</name>
</id>
<attribute>
<name>movie_title</name>
<type>String</type>
<null_value></null_value>
</attribute>
</structure>
</dictionary>
Somebody who ever encountered the same problem?Thankx！

Answer 1

I found the reason that because of the dic source (mysql 5.1) is too old to be compatible with the high version clickhouse. Finally I change clickhouse's version back to 19.14.6.