[BUG] Unable to migrate more than one subscription at once: qmail-newu: fatal: unable to move users/cdb.tmp to users/cdb

Symptoms

Unable to migrate more than one subscription at once, the process fails with the following error in Tools & Settings > Migration & Transfer Manager > 203.0.113.2 > example.com > Details:

DEBUG An error occurred during domain creation: mailmng-core failed: /var/qmail/bin/qmail-newu execution failed:
qmail-newu: fatal: unable to move users/cdb.tmp to users/cdb

Cause

The issue is caused by bug with ID #PPPM-10116.

Resolution

The following workaround is available:

1. Log in to target Plesk;

2. Remove the subscriptions that failed to be transferred going to Subscriptions > example.com > Remove Subscription

3. Connect to the target server via SSH;

   Note: if direct SSH access to the server is not possible, contact server administrator for further assistance.

4. Back up migration configuration files:

   # find /usr/local/psa/var/modules/panel-migrator/sessions/*/config.ini -exec cp -a {} {}.backup ;

5. Add multithreading-num-workers = 1 parameter in GLOBAL section from migration configuration files:

   # sed -i ‘s/[GLOBAL]/[GLOBAL]nmultithreading-num-workers = 1/g’ /usr/local/psa/var/modules/panel-migrator/sessions/*/config.ini

   Note: It is possible to remove multithreading-num-workers = 1 parameter from migration configuration files with the following command:

   # sed -i ‘s/multithreading-num-workers = 1//g’ /usr/local/psa/var/modules/panel-migrator/sessions/*/config.ini

6. Run the migration again by going to Tools & Settings > Migration & Transfer Manager > 203.0.113.2 > List of subscriptions > Select the subscriptions > Migrate