Hello,
Currently, the influxdb-client-csharp client uses outdated RestSharp properties. This causes RestSharp to crash when you try to update the RestSharp NuGet reference in your project, because it can no longer access the property.
I've already created pull request #719 with the affected code sections adjusted. Please take a look at the PR and implement it as soon as possible, or alternatively, I can create a PR using your current RESTSharp version, fixing only the deprecated property.