I started migration using
ppa-transfer generate-migration-list config.ini command, but it failed with error below:
ProtocolError: <ProtocolError for admin:firstname.lastname@example.org:8440/RPC2: 401 Unauthorized> [ERROR] | Unexpected error: '<ProtocolError for admin:email@example.com:8440/RPC2: 401 Unauthorized>', migration is aborted. See the traceback above for more information.
Password with special symbol '%' could not be properly passed via API request, as a result authorization fails. The issue is considered to be as a software issue, internal request it #TP-144350. It will be fixed in future product updates.
As a workaround you may want to change password to another one without symbol '%'.