define( 'DOMAIN_CURRENT_SITE', 'xxx.de' );

in the wp-config file. This does not seem to be getting updated automatically and hence the change needs to be made manually (and also in the database).

Sorry, I didn't mention that it was a mutlisite installation before because I couldn't see any reason for that to affect the smtp plugin settings.

You could also enable remote SSH support for us via the dashboard, if you want us to debug this directly. If you do, please send us a mail to support@cloudron.io with some context which domain your Cloudron dashboard is on and which domain this issue can be seen.

Looks like the wordpress plugin relies on some live domain validation which fails.

Thanks for looking into this. The lines posted are the last two, here are also the ones that precede them:

Aug 23 12:51:03 => Changing permissions
Aug 23 12:51:03 box:settings initCache: pre-load settings
Aug 23 12:51:03 box:taskworker Starting task 1602. Logs are at /home/yellowtent/platformdata/logs/.../apptask.log
Aug 23 12:51:03 box:tasks 1602: {"percent":2,"error":null}
Aug 23 12:51:03 box:apptask xxx.de startTask installationState: pending_location_change runState: running
Aug 23 12:51:03 box:tasks 1602: {"percent":10,"message":"Cleaning up old install"}
Aug 23 12:51:03 box:shell reload spawn: /usr/bin/sudo -S /home/yellowtent/box/src/scripts/restartservice.sh nginx
Aug 23 12:51:03 => Updating db settings
Aug 23 12:51:03 box:apptask xxx.de deleting app containers (app, scheduler)
Aug 23 12:51:03 box:shell removeCollectdProfile spawn: /usr/bin/sudo -S /home/yellowtent/box/src/scripts/configurecollectd.sh remove ...
Aug 23 12:51:03 box:shell removeCollectdProfile (stdout): Restarting collectd
Aug 23 12:51:04 Success: Updated the constant 'DB_HOST' in the 'wp-config.php' file with the value 'mysql:3306'.
Aug 23 12:51:04 box:shell removeCollectdProfile (stdout): Removing collectd stats of ...
Aug 23 12:51:04 box:shell removeLogrotateConfig spawn: /usr/bin/sudo -S /home/yellowtent/box/src/scripts/configurelogrotate.sh remove ...
Aug 23 12:51:04 Success: Updated the constant 'DB_NAME' in the 'wp-config.php' file with the value 'xxx'.
Aug 23 12:51:04 Success: Updated the constant 'DB_USER' in the 'wp-config.php' file with the value 'xxx'.
Aug 23 12:51:04 Success: Updated the constant 'DB_PASSWORD' in the 'wp-config.php' file with the value 'xxx'.
Aug 23 12:51:04 => Updating redis settings
Aug 23 12:51:04 Success: Updated the constant 'WP_REDIS_HOST' in the 'wp-config.php' file with the value 'xxx'.
Aug 23 12:51:04 Success: Updated the constant 'WP_REDIS_PORT' in the 'wp-config.php' file with the value '6379'.
Aug 23 12:51:04 Success: Updated the constant 'WP_REDIS_PASSWORD' in the 'wp-config.php' file with the value 'xxx'.
Aug 23 12:51:05 => Updating domain related settings
Aug 23 12:51:05 Success: Updated the constant 'WP_HOME' in the 'wp-config.php' file with the value 'https://xxx.de'.
Aug 23 12:51:05 Success: Updated the constant 'WP_SITEURL' in the 'wp-config.php' file with the value 'https://xxx.de'.
Aug 23 12:51:06 Success: Value passed for 'siteurl' option is unchanged.
Aug 23 12:51:06 Success: Value passed for 'home' option is unchanged.
Aug 23 12:51:07 => Configuring smtp-mailer plugin
Aug 23 12:51:08 ==> Configuring smtp-mailer plugin for https://xxx.de/
Aug 23 12:51:08 Error: Site 'xxx.de/' not found. Verify `--url=<url>` matches an existing site.
Aug 23 12:51:08 Error: Site 'xxx.de/' not found. Verify `--url=<url>` matches an existing site.