This can happen if you have low are nearly out of disk space. If you have used 95% or more of your disk space, disk, Elasticsearch enforces a read-only index (no update and adding to the index is allowed only deletion will work).
**You just have to clean up your disk to have more than 5% free disk space (anyway a good idea) and restart Axon.ivy and it should work again.**
See detailed information in the [Elasticsearch reference][1] about the configuration properties and what happens when.
[1]: https://www.elastic.co/guide/en/elasticsearch/reference/current/disk-allocator.html