Error while restoring a domain or during a migration: filemng: Error occurred during /usr/bin/base64 command

Symptoms

An error appears in /usr/local/psa/PMM/rsessions/<session_id>/migration.log while restoring a domain or during a migration:

CONFIG_TEXT: Plesk restore report problem:
Execution of /usr/local/psa/admin/bin/backup_restore_helper --restore-subscription example.com -ignore-nonexistent-options failed with return code 1
Stdin is
</web-settings><composer-instances>
<composer-instance path="httpdocs/wp-content/plugins/jetpack/composer.json"/>
</composer-instances></subscription-info>
<stderr>filemng failed: filemng: Error occurred during /usr/bin/base64 command.

Cause

A WordPress plugin was removed, its composer.json was not found during the backup restoration. This is a Plesk bug with ID PPPM-7222 which will be fixed in future updates.

Resolution

This error can be safely ignored. Or as a workaround, do the following whenever some WordPress plugin is removed:

1. Login into Plesk;
2. Press Scan button in WordPress > WordPress instance name to synchronize changes with Plesk database.
3. Create a new backup at Tools & Settings > Backup Manager or re-run migration in Tools & Settings > Migration Manager.