Unable to start Plesk migration: urlopen error [Errno 99] Cannot assign requested address

Symptoms

Cannot start Plesk migration:

urlopen error [Errno 99] Cannot assign requested address

Cause

Plesk Migrator tries to check connection to the target host. It takes the first IP from
IP_Addresses
table and tries to establish connection. The first IP is misconfigured or does not exist on the target server.

Resolution

1. Log in to target Plesk server

2. Go to Tools & Settings > IP addresses and click Reread. Repair link should appear next to the problematic IP address. Click Repair or remove the address from Plesk.

3. Finish current migration with Tools & Settings >  Migration & Transfer Manager > Finish Migration and start over.