Plesk Migration fails: some files vanished before they could be transferred (code 24)

Symptoms

• Plesk Migrator fails to migrate a subscription:

  Failed to copy web files for subscription 'example.com'
  Migration tools tried to perform operation in 3 attempts: Rsync failed to copy files from the source server 'source' (203.0.113.2) to target Plesk server:
  This could happen because of a network connection issue. Run migration for that subscription once more.

• The following is logged to C:\Program Files (x86)\Plesk\var\modules\panel-migrator\sessions\yyyy_mm_dd\debug.log

  D|ST1|core.runners.base|example.com.in||stderr: file has vanished: "/example.com/httpdocs/सर्à¤" (in vhosts)
  D|ST1|core.runners.base|example.com.in||rsync warning: some files vanished before they could be transferred (code 24) at main.c(1637) [generator=3.1.1]

Cause

The filename has unsupported characters, or is too long.

Resolution

1. Log in to Plesk on the source server
2. Go to Domans > example.com > File Manager and rename the file (सर्à¤ in the example from the symptoms above)
3. Try to migrate the subscription again

Alternatively, files can be transferred manually without renaming them, and the error can be ignored.