Facing issue "Error generating JSON encoded response: Malformed UTF-8 characters, possibly incorrectly encoded" when call api

[Nhat]

Hi All,

I'm using whmcs version 7.2.3. I'm trying intergerate whcms with third-party system. However, while intergrate i've used to GetClientsProducts api to get product uid to map with client product service (I'm thinking WHY in GetInvoice, GetOrders api not response include product uid, because many case pid very necessary ???). I see whmcs support api very bad. Now, i could not continue my work cause by this issue. Someone have solution please give me to resolved it.

Many thanks!