I do not know why it happens.

It must be a connection error at neo4j: Connection to Instance Failed

Possible causes

The instance may be paused, offline, or non-existent.

Network or internet issues, or restricted access on connection port.

Typo or error in the connection URL.

How to fix

If using Aura DB, confirm the instance status is 'Running' on the Neo4j Aura Console

Ensure stable internet connectivity and port access (e.g. port 7687).

Review the connection URL, particularly the database ID.

Error details

ServiceUnavailable

Could not perform discovery. No routing servers available. Known routing table: RoutingTable[database=system, expirationTime=0, currentTime=1754384376639, routers=[], readers=[], writers=[]]