3285201 - API upsert error "keyString cannot be blank"

When you use OData API to upsert data, it returns error "keyString cannot be blank".

You check the payload but cannot find any fields left blank.

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SAP SuccessFactors HXM Suite

This error means the request has a blank key for the entity.

It usually happens when you add parenthesis appending the entity, but didn't specify the key in the parenthesis.

Please remove the parenthesis, or instead specify the correct key in the parenthesis.

OData API, business key, entity, payload, parenthesis  , KBA , LOD-SF-INT-ODATA , OData API Framework , Problem