How to fix ReplicaAlreadyExistsException: Replica already exists in the global table in DynamoDB

Use the AWS CLI to see which regions already have replicas for your table:

aws dynamodb describe-global-table \
  --global-table-name your-table-name \
  --region us-east-1

Look at the ReplicationGroup output to see all active replicas. Each region should appear only once.

If you deleted a global table previously, its replicas might persist as standalone tables in other regions. Check each region:

aws dynamodb list-tables --region eu-west-1
aws dynamodb list-tables --region ap-southeast-1
# Check all regions where you intended to have replicas

If you find orphaned tables with the same name as your global table, they need to be deleted before recreating the global table.

If you found orphaned replica tables from a previous global table setup, delete them:

aws dynamodb delete-table \
  --table-name your-table-name \
  --region eu-west-1

aws dynamodb delete-table \
  --table-name your-table-name \
  --region ap-southeast-1

Wait for all orphaned tables to be completely deleted before proceeding (this can take a few seconds).

Before adding a new replica, confirm the target region is not already in the global table:

aws dynamodb describe-global-table \
  --global-table-name your-table-name \
  --region us-east-1 | grep -A 5 ReplicationGroup

If the region you want to add is already listed, you do not need to add it again.

Use separate API calls for better reliability. First update to add a new replica:

aws dynamodb update-global-table \
  --global-table-name your-table-name \
  --replica-updates '[
    {
      "Create": {
        "RegionName": "eu-west-1"
      }
    }
  ]' \
  --region us-east-1

AWS recommends issuing separate requests for adding or removing replicas instead of combining both operations in a single call.

If you are using the current version of global tables (2019.11.21), the UpdateTable API provides a simpler approach:

aws dynamodb update-table \
  --table-name your-table-name \
  --stream-specification StreamEnabled=true,StreamViewType=NEW_AND_OLD_IMAGES \
  --region us-east-1

Then add replicas to the table definition. This is more flexible and consumes less write capacity than the legacy API.