Post request issue with some android devices (new or old) in Xamarin-forms cross platform project

Question

Post request issue with some android devices (new or old) in Xamarin-forms cross platform project

Huynh 1

I have encountered 404 error response when making Post requests to a specific API call on some Android devices. It does not happen with any of iOS devices. There are no error logs from the server-side. The issue was reported by some of the end-users. It does not happen all the time for some of those devices that encountered this issue, but a very small number of those devices actually encountered this issue 100% of the time when trying to make post request to said API. None of my test devices can't replicate the problem, so I can't think of any other way to try and solve this issue. Please advise.

Code snippet of the post request:

String postUrl = ConfigurationMyApp.MyAppBaseUrl + "api/MyAppApi/SaveData";
HttpContent contentPost = new StringContent(JsonConvert.SerializeObject(graniteSignOutForm), Encoding.UTF8, "application/json");            
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, postUrl);
    request.Content = contentPost;

HttpResponseMessage httpResponseMessage = client.SendAsync(request, HttpCompletionOption.ResponseContentRead).Result;

JarvanZhang 23,971 Reputation points

2020-12-25T04:12:37.22+00:00

Hi, Huynh-5565. The 404 error is due to the server client, please check the error logs of the server side. If this issue only occurs on some devices, try to compare the similaritiesof these devices to analyze the cause.
Huynh 1 Reputation point

2020-12-28T15:32:44.537+00:00

There were no error logs on the server-client every time I checked for this particular error each time the error occurred (based on the timeframe when it happened) and reported by the EU. I've tried to gather the info of those devices with the issue, but have not got enough data to make any determination why the error occurred.
Hence I'm here looking for more insights or potential solutions that I could try.
John Hardman 261 Reputation points

2020-12-28T15:39:34.337+00:00

@Huynh

I suggest adding some error reporting, so that when the 404 is received, you report the URL and the properties (such as BaseAddress and DefaultRequestHeaders) of the HttpClient instance being used (and ideally the full content of the POST message as well). As you report that the 404 is received 100% of the time on the devices where it happens, it's unlikely to be a threading problem, so simply reporting these details should help identify the cause.

It's always handy to have the option to log the detail of HTTP traffic sent and received so that you can investigate these sorts of issues, although full logging might be something to restrict to builds distributed to alpha and beta testers.

Also, which HttpClient Implementation have you specified in your Android project's properties, and which SSL/TLS Implementation?
What are the Minimum and Target Android versions?
What are the Android versions of the devices exhibiting the problem?
Huynh 1 Reputation point

2020-12-28T18:21:01.473+00:00
Also, which HttpClient Implementation have you specified in your Android project's properties, and which SSL/TLS Implementation?

HttpClient implementation: "Android"

SSL/TLS implementation: "Default (Native TLS 1.2+)

What are the Minimum and Target Android versions?

Minimum: Android 5.0 (API level 21 - Lollipop)

Target: Android 10.0 (API level 29 - Q)

What are the Android versions of the devices exhibiting the problem?
Q (Android 10.0)
Oreo (Android 8.0)
and probably more
John Hardman 261 Reputation points

2020-12-29T19:26:52.933+00:00

From one of the devices where the problem occurs, what is the value of postUrl, and what are the values of the properties (such as BaseAddress and DefaultRequestHeaders) of the HttpClient instance being used? (obviously, be aware of any security concerns when answering this).

If you can also share the full content of the POST message as well, that could help identify the problem (but again, be aware of any security concerns when sharing).