How to replicate:
- create index with schema where you uniqueKet is integer
- set your unique key type to integer
- deploy your index
under http://host:8080/solr/admin/ - you will get "missing core name in path"
- change type of your uniqueKet to srting
- undeploy and deploy index
Its quite confusing as 1.5 is not properly reporting errors and you need to be lucky to find that reason on your own.