I have an issue where running a discovery is failing. This has been working for years. When looking at the host configuration > discovery there is the red "!" and it says "Value should be a JSON object." Every server, new or old, is now failing where it used to work.
Our script or agent config hasn't changed. I have recently updated the server and all proxies except 1 to 3.2.4. The discovery items are working on servers running under the one proxy that is still on 3.0.4.
I ran zabbix_get from the proxy to the servers to see what was being returned from the discovery, and it is in fact good JSON. I used an online validation tool to verify.
This is an example of the discovery that shows as failed from a 3.2.4 proxy:
And here is a discovery that is working from the 3.0.4 proxy:
When compared, they are the exact same. The only difference is what proxy they are going through. Attached are screenshots of the failed and working configuration > host > discovery rules pages.