Mariadb replication slave can only access information_schema db I had a master-slave set up working fine until a power outage on the slave. Now I get

error connecting to master 'repl@10.0.0.1:50000' - retry-time: 60
maximum-retries: 86400
message: Access denied for user 'repl'@'localhost' (using password: YES)

The password has not changed and I can log in to the database using
slave-host$ mysql -h10.0.0.1 -P50000 --user=repl --password='secret'

However once logged in I cannot see any databases except information_schema. Trying use &lt;my_db_name&gt; gives an access denied error.
On the master
master-host: mysql&gt; show grants for repl@localhost;
GRANT REPLICATION SLAVE ON *.* TO
  'repl'@'localhost' IDENTIFIED BY PASSWORD '*xxxxx'

I've tried re-granting access, FLUSH PRIVILEGES, START/STOP SLAVE; in various combinations but I'm not getting anywhere.
Nb. the host at 10.0.0.1 has an SSH tunnel setup to the datbase host, so grants for repl@localhost are appropriate because the master sees it as local traffic.
Master and slave both on:  10.1.26-MariaDB-0+deb9u1
Odd.

The fix seemed to be to change the password.


stop slave
change password for repl user at master.
on slave: change master to master_password = 'new pass'
start slave