Repository service api Virtual proxy update

[Anonymous]

I want to update Virtual proxy settings via repository service api (https://help.qlik.com/en-US/sense-developer/June2018/apis/repositoryserviceapi/index.html#f0190c0b6c...)

But when i call this api with with modified properties i always get response 409 - Conflict.

How can i call this api? Do i need set something special?