why the indexers are initiating rolling-restart automatically?

[AbilashSe]

Indexers were restarted automatically with the below error, could anyone please help me on this?

06-20-2018 13:48:19.578 +0000 WARN HttpListener - Socket error from XXXXX while accessing /services/data/indexes: Broken pipe
06-20-2018 13:48:19.971 +0000 WARN HttpListener - Socket error from XXXXX while accessing /services/data/indexes: Broken pipe
06-20-2018 13:48:20.011 +0000 WARN HttpListener - Socket error from XXXXX while accessing /services/data/indexes: Broken pipe

[AbilashSe]

We are getting the below error as well in the splunkd.log.

"Cannot apply bundle, error=Cannot apply (or) validate configuration settings. Bundle reload is in progress"