Unable to delete the IP address in Plesk: cannot delete main IP on interface

Symptoms

• The IP address '203.0.113.2' can not be removed from Plesk > Tools & Settings > IP Addresses menu with the following error:

  PLESK_ERROR: Error: ifmng failed: 203.0.113.2: cannot delete main IP on interface

• The IP address '203.0.113.2' is not the main IP address of the server:

  # plesk db "select ip_address,main from IP_Addresses"
  +---------------+-------+
  | ip_address | main |
  +---------------+-------+
  | 203.0.113.2 | false |
  | 203.0.113.3 | true |
  +---------------+-------+
  2 rows in set (0.00 sec)

Cause

The IP address '203.0.113.2' was configured manually on the server on the non-alias network interface. Plesk utility ifmng can not delete such an IP address to avoid situations when the server won't have an IP address left.

Resolution

1. Connect to the server via SSH.
2. Manually remove the IP address '203.0.113.2' from the interface using the native OS commands.
3. Log into Plesk.
4. Navigate to Tools & Settings > IP Addresses and click on the Reread IP button.
5. Select the IP address '203.0.113.2' for removal and click on the Remove button. Confirm removal.