If you accidentally locked all the users including SAP* and DDIC in one of the clients.

This is another method to UNLOCK ALL users.

Start Oracle Server manager ( I assume you are on Oracle)
connect internal
update sapr3.usr02 set uflag='0' where mandt='399';

When users are locked, the uflag is set to 64.

Finish, just query to check.

select bname, uflag from sapr3.usr02 where mandt='399';

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