Database Installer steps all OK but cannot login mysql error 1045

[Loggy]

Ubuntu 20.04 LTS recent upgrade

nginx 1.18.0 fast_cgi - this is the only web page, the server is IP protected, running https with only trusted port IP access, no client caching (expires 0;)

php7.4-fpm with a single pool.d file that runs under www-data:mail, Postfix/Dovecot working OK - forwarding, parsing etc mail or writing to Maildir.

The final stage is to implement Roundcube to give complete control of my email. So mariadb 10.3.31, roundcube 1.4.3 are from Ubuntu repositories.

The database user roundcube and database roundcube as per the INSTALL instructions, char utf8, collate utf8_general_ci.

I had to add the privileges individually (set Select_priv="Y" where User = "roundcube" - grant all did nothing).  They were flushed and I am able to add a table to roundcude and insert into it from user roundcube as well.

The installer runs and checks OK - DSN (write), DB Schema, DB Write and DB Time are all OK.  I can send mail out and the IMAP login works (SORT capability: yes)

But when I load the root page (ie /index.php), I get the DATABASE ERROR: CONNECTION FAILED! message!  The $err_str is SQLSTATE[HY000][1045] which I print_r from index.php

I have tried everything I can think of now, after a week of googling.  The message suggests it is a password error but I have zillion-checked this. 

I can login normally using mariadb -p -u roundcube roundcube.  I can login to mariadb root OK.

I can access mysql using a small php program and mysqli_connect etc. which works from different users mail, www-data, postfix and dovecot (they are all in the same group anyway)

I have uninstalled and reinstalled both mariadb and roundcube (getting desparate!).

It is as if the connection in rcube_db is doing something different to the connection in test.php as per the connection in config.inc.php

[I have left the installer directory in the root for the moment.]

Very puzzled.  Any hints/suggestions/ideas other than migrating to gmail?

TIA

[Loggy]

Whatever was the cause, I updated to the latest stable 1.4.11 from the instructions on https://www.mysterydata.com/install-and-update-roundcube-latest-version-on-ubuntu-vestacp/

And the problem has disappeared!  It immediately connected with all my mail in the Maildir tree visible.

I did notice that while my password was correctly updated in /etc/roundcube/debiand-db-roundcube.php it had not been copied into /etc/roundcube/debian-db.php so this may have been the problem all along.

And as my password includes a few special characters which were originally translated into %xx in config/config.inc.php I left them as special characters in the new config.inc.php and it still worked.

A message to Ubuntu package maintainer is on its way!

Now to learn the ins and outs of running roundcube which looks very nice.