Error: Permission Denied to Start WAL Sender

Issue

Connection setup tests succeed, but syncs fail with the following error:

Unknown failure. Unhandled Classified Exception. permission denied to start WAL sender Detail: Only roles with the REPLICATION attribute or privileges of the "rds_replication" role may start a WAL sender process.

Environment

• Connector: Amazon RDS PostgreSQL or Amazon Aurora PostgreSQL
• Incremental sync method: Logical replication

Resolution

To resolve this issue:

1. Grant the rds_replication role to the configured Fivetran user by running the following command:

   GRANT rds_replication TO <username>;
   

2. Ensure the user automatically inherits the role's privileges:

   ALTER ROLE <username> INHERIT;
   

3. Re-run the sync.

Cause

This issue occurs when the Fivetran database user doesn't have the rds_replication role or doesn't inherit its privileges.

You can run the following query as the Fivetran user to verify its role membership and active privileges:

SELECT
    current_user,
    session_user,
    current_database(),
    inet_server_addr(),
    inet_server_port(),
    pg_has_role(current_user, 'rds_replication', 'MEMBER') AS is_member,
    pg_has_role(current_user, 'rds_replication', 'USAGE') AS privilege_is_active;

• If is_member returns false, the user hasn't been granted the rds_replication role.
• If is_member returns true and privilege_is_active returns false, the user has the role but doesn't inherit its privileges.