Working on upgrading a 3.x limesurvey instance, to 5.x

The upgrade seemed to go fine, database updates ran, most of admin pages working.

When I go to the Plugins configuration page, I get:
500: Internal Server Error
Missing configuration file for plugin Authdb, looked in location /var/www/html/survey/plugins/Authdb/config.xml

This is strange, as the plugin is Core provided, and located in ../survey/application/core/plugins/Authdb

Any help appreciated, Thank You!
 

You upgrade to las 5.X version ?

If yes : report the issue
I think you can update manually in the DB

What LS version (for 5.X) ?
bugs.limesurvey.org/view.php?id=17361#c64830
 

Latest stable, 5.0.7

Both of these showed plugin_type = user in the plugins table.

I manually updated these column values to plugin_type = core .. to proceed

Looks to me in around lines 3773-3780 or so ..
./application/helpers/upgrade/updatedb_helper.php

need two more lines:
$insertPlugin('Authdb');
$insertPlugin('ComfortUpdateChecker');

Also strange, the plugins page shows two ComfortUpdateChecker plugins, but there is only one record in the database table, plugins

All in all, everything else seems to be working good though after the upgrade ..