Mail migration fails: Exception of type 'System.OutOfMemoryException' was thrown

Symptoms

Errors in %plesk_dir%\var\modules\panel-migrator\sessions\20170721181945\target-server\mail\example.com\john.doe\mail-restore.log with enabled debug:

[WARNING] Exception: Exception of type 'System.OutOfMemoryException' was thrown.
[DEBUG] System.OutOfMemoryException: Exception of type 'System.OutOfMemoryException' was thrown.
 at MailMigrator.Utils.StreamUtils.ReadExactly(Stream stream, Int32 count)
 at MailMigrator.Core.Dumps.StreamDumpReader.ReadString()
 at MailMigrator.Core.Dumps.StreamDumpReader.ReadMessage()
 at MailMigrator.MailMigrator.PerformRestore(IDumpReader dumpReader, MailAccount account, IRestoreProvider provider)
 at MailMigrator.MailMigrator.ParseArgumentsAndRunCommand(String[] args)
 at MailMigrator.MailMigrator.Main(String[] args)
[ERROR] Error: Exception of type 'System.OutOfMemoryException' was thrown.

Cause

This is bug with ID PMT-3868 which is planned to be fixed in the next Plesk Migrator update.

Resolution

Until a fix become available, use the following workaround:

1. Connect to the server using RDP.
2. Rename %plesk_dir%\var\modules\panel-migrator\thirdparties\MailMigratorWindows_1.6\MailMigrator.exe into MailMigrator.exe.bk
3. Download and unpack the attached custom fix and place it into %plesk_dir%\var\modules\panel-migrator\thirdparties\MailMigratorWindows_1.6 directory.