This article offers a solution to resolve the error.
Config Update is failing with below error
Validation Failed Problems: 1: Error: "Item is not unique" @ "/config/authority/router/90ec7791df57/node/node0/device-interface/ge-0-0/network-interface/ge-0-0/tenant-prefixes/blacklist_ddos.internet/source-address"
Note: In the above error blacklist_ddos network object is holding duplicate IP prefix entries due to which config update is failing.
Review the affected network object and identify any duplicate IP prefix entries.
Remove the duplicate entries and retain only a single instance of each prefix.
Retry the configuration update after ensuring all network object entries are unique.