Hi Miran,
I think your API query framing is not correct, end point must be placed after the body, for your reference please see the below PFREST/SVOS API, as API has a standardized query syntax hence almost all APIs' will have same structure.
Below API creates a ldev in the storage [we bypassed the SSL handshake]
curl -k -v -H "Accept:application/json" -H "Content-Type:application/json" -u <user_id>:<password> -X POST -d " { \"poolId\" : \"1\",\"byteFormatCapacity\" : \"10G\"}" "https://XX.XX.XX.XX:443/ConfigurationManager/v1/objects/ldevs"
If you could tell me which API you are trying and what do you want to accomplish then that would be helpful for us to be more specific.
Thanks
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Prasenjit Chatterjee
Software Engineer- Test
Hitachi Vantara
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