I am facing "406 not acceptable nginx" error when I call send grid api

Question

I am facing

"406 not acceptable nginx"

..error when I call send grid api

Sometimes it gives me json response perfect but after 2 3 minutes it gives me:

"406 not acceptable" error

We have been facing this error for 3 months. Please help us.

I used the below code in c#

HttpClient client1 = new HttpClient();   
client1.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json; charset=utf-8");
client1.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", "authentication key");
client1.DefaultRequestHeaders.Add("on-behalf-of", "email id");
HttpResponseMessage response1 = client1.GetAsync("https://api.sendgrid.com/v3/senders").Result;
Response.Write(response1.Content.ReadAsStringAsync().Result);

Answer 1

I worked through this issue with Sendgrid support and in my case it was concluded that this error corresponded with the request being issued from an IP address that was blocked by their security policy. If you are making these requests from a cloud function environment like Firebase or Lambda, where the IP address can change with each instance, this may be the reason. Their support team may be able to add IP addresses to their allow-list but a better solution may be to route your request through a dedicated IP address.