# Cannot get MySQL var character\_set\_server

**URL:** <https://forums.percona.com/t/cannot-get-mysql-var-character-set-server/25741>\
**Category:** Percona XtraDB Cluster 5.x\
**Created:** [October 7, 2023, 10:58am UTC](https://forums.percona.com/t/cannot-get-mysql-var-character-set-server/25741 "2023-10-07T10:58:58Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![marcio](https://avatars.discourse-cdn.com/v4/letter/m/f19dbf/32.png) [@marcio](https://forums.percona.com/u/marcio)\
**Post date:** [October 7, 2023, 10:58am UTC](https://forums.percona.com/t/cannot-get-mysql-var-character-set-server/25741/1 "2023-10-07T10:58:58Z")

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Hello!!

After I updated the server packages to percona-toolkit-3.5.5-1.el8.x86\_64 I am not start the pt-kill daemon.

I am getting this error:

Cannot get MySQL var character\_set\_server: DBD::mysql::db selectrow\_array failed: Native table ‘performance\_schema’.‘session\_variables’ has the wrong structure [for Statement “SHOW VARIABLES LIKE ‘character\_set\_server’”] at /usr/bin/pt-kill line 2165.

This is all the packages:  
percona-toolkit-3.5.5-1.el8.x86\_64  
percona-release-1.0-27.noarch  
Percona-XtraDB-Cluster-shared-57-5.7.43-31.65.1.el8.x86\_64  
Percona-XtraDB-Cluster-57-5.7.43-31.65.1.el8.x86\_64  
percona-xtrabackup-24-2.4.28-1.el8.x86\_64  
Percona-XtraDB-Cluster-client-57-5.7.43-31.65.1.el8.x86\_64  
Percona-XtraDB-Cluster-server-57-5.7.43-31.65.1.el8.x86\_64

Any help about it ?

Thank you.

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<div class="post-metadata">

**Author:** ![matthewb](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/matthewb/32/34_2.png) [@matthewb](https://forums.percona.com/u/matthewb)\
**Post date:** [October 8, 2023, 12:53pm UTC](https://forums.percona.com/t/cannot-get-mysql-var-character-set-server/25741/2 "2023-10-08T12:53:33Z")

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> [@marcio](#):
>
> Native table ‘performance\_schema’.‘session\_variables’ has the wrong structure

You need to run `mysql_upgrade` to fix the tables and then restart MySQL. Looks like you upgraded MySQL recently and forgot to run this required tool.

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<div class="post-metadata">

**Author:** ![marcio](https://avatars.discourse-cdn.com/v4/letter/m/f19dbf/32.png) [@marcio](https://forums.percona.com/u/marcio)\
**Post date:** [October 29, 2023, 5:42pm UTC](https://forums.percona.com/t/cannot-get-mysql-var-character-set-server/25741/3 "2023-10-29T17:42:13Z")

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Hi @matthewb.  
Please explain:

- this command must be run in each node running XtraDB or can it be in just one?
- after do that, restart all instances?  
Thank you.

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<div class="post-metadata">

**Author:** ![matthewb](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/matthewb/32/34_2.png) [@matthewb](https://forums.percona.com/u/matthewb)\
**Post date:** [October 30, 2023, 2:24pm UTC](https://forums.percona.com/t/cannot-get-mysql-var-character-set-server/25741/4 "2023-10-30T14:24:25Z")

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Best practice: Shut down all but 1 node. `mysql_upgrade` 1 node. Restart node. Start other node, letting it SST/IST. Start last node.