After installing the ElasticSearch KFF engine and Import Utility, when attempting to import a hash set (NSRL, etc.) the error message below appears.
Waited too long for cluster health state Yellow.
The steps below will resolve this issue.
1. Stop the ElasticSearch service in Windows Services (Start >> Run >> services.msc).
2. Delete the data folder for ElasticSearch (the folder name is typically the same as your system hostname).
3. Restart the ElasticSearch service.
4. Try the NSRL data import again.
This issue is caused by a corrupt ElasticSearch installation.