When trying to access the below API documentation URL, it throws an error
https://<hostname>/niku/rest/describe/index.html
Error: failed to parse JSON/YAML response
Clarity : 15.9.3, 16.0.x, 16.1.x, 16.2.x, 16.3.2
Often this can be resolved by simply flushing the Clarity caches:
If this doesn't resolve the issue, a restart of the app server may be necessary.