Hi @manish_bansal: Yes if one is already building on a bucket, another index build on same bucket will fail but will be scheduled for building in the background. The error you might be seeing would be like “retried building in the background”. As you rightly observed, it is not ideal to build indexes one by one. When you upgrade to v6.5, please do consider upgrading your script to build all indexes in a given bucket at once. As you might already know, the benefit of building multiple at once is parallel building of indexes and better use of streaming data from the Data Service nodes with efficient network utilization.