Error when syncing a subscription with a service plan or customizing subscription's resources in Plesk: Unable to allocate the required amount of resources

Resolution

1. Connect to your Plesk server via SSH.

2. For safety reasons, create a backup of the Plesk database:

   # plesk db dump psa > /root/psa_backup.sql

3. Find ID of the customer which owns the subscription:

   Note: Replace example.com with a subscription name in the command below: 

   # plesk db "SELECT cl.id AS 'Client ID', cl.pname AS 'Name', cl.login AS 'Login', d.name AS 'Domain' FROM clients cl, domains d, DomainServices ds, IpAddressesCollections ipc, IP_Addresses ip WHERE d.id = ds.dom_id AND d.cl_id = cl.id AND ds.type = 'web' AND ds.ipCollectionId = ipc.ipCollectionId AND ip.id = ipc.ipAddressId AND d.name='example.com'"
   
   +-----------+----------+----------+-------------+
   | Client ID | Name     | Login    | Domain      |
   +-----------+----------+----------+-------------+
   |        68 | John Doe | john_doe | example.com |
   +-----------+----------+----------+-------------+

4. Set customer's limits_id to 0:

   # plesk db "update clients set limits_id = 0 where id = 68"

5. Re-sync the subscription / customize subscription resources.