Mail migration to Plesk using Site Import or Plesk Migrator fails: ‘utf-8’ codec can’t decode byte 0xfc in position 828: invalid start byte

Symptoms

Mail migration using Site Import or Plesk Migrator fails:

# |D|MT|core.cli.common_cli|||Failed to backup message #8 (UID 708) in IMAP folder '"INBOX.Trash"': 'utf-8' codec can't decode byte 0xa3 in position 2406: invalid start byte
=|D|MT|core.cli.common_cli|||
=|D|MT|core.cli.common_cli|||Failed to backup message #11 (UID 711) in IMAP folder '"INBOX.Trash"': 'utf-8' codec can't decode byte 0xb6 in position 3260: invalid start byte
=|D|MT|core.cli.common_cli|||
=|D|MT|core.cli.common_cli|||Failed to backup message #16 (UID 716) in IMAP folder '"INBOX.Trash"': 'utf-8' codec can't decode byte 0xa3 in position 3142: invalid start byte
=|D|MT|core.cli.common_cli|||
=|D|MT|core.cli.common_cli|||That is a critical error, migration was stopped.
+|E|MT|core.cli.common_cli|||Failed to connect to the source server and copy mail messages
=|E|MT|core.cli.common_cli|||Cause: Command execution failed on the local server with non-zero exit code.

Cause

Bug PMT-5354 in Site Import and Plesk Migrator extensions.

The bug was fixed in Site Import 1.8.1 and Plesk Migrator 2.26.1.

Resolution

Update extensions Site Import and/or Plesk Migrator to the latest versions.