[Koha] Upgrade problem Debian Packages

Following an upgrade form 16.05 to 17.11 using the packages (and koha-restore) on Debian Jessie I get the following error when trying to access the staff or opac interface; "DBIx::Class::Storage::DBI::catch {...} (): DBI Connection failed: Access denied for user 'koha_instance'@'localhost' (using password: YES) at /usr/share/perl5/DBIx/Class/Storage/DBI.pm line 1490. at /usr/share/koha/lib/Koha/Database.pm line 100" I did notice the error during koha-restore 'DROP USER koha_instance failed' (approx). I'd appreciate some help. Clint.