SymptomsDomain migration fails with the following error:
Execution of /usr/local/psa/admin/plib/api-cli/domain_pref.php --update TestDomain.com failed with return code 4.
Object not found: Domain TestDomain.com
This error appears if mixed-case is used for the domain name and spamassassin is enabled for the mailbox.
ResolutionRename the domain name using lower-case letters only and perform domain migration once again.
After that migration should be completed without this error.
This problem has been fixed in Parallels Panel 10.4. Consider upgrade Parallels Panel on your server.