Encoding 1251 data could not be found

[XFox111]

Description

On some devices (Google Play testers) application throws System.NotSupportedException

Reproduction steps

Unknown, possibly changing device regional settings to (?)
According to video reports, It happens only on the export process

Expected behavior

No exception should be thrown. The app should export schedule

Screenshots

Video demos are attached to Google Play testing reports and will be sent by assignees' demand

Environment

Please complete the following information:

• Device: Samsung Galaxy S3, S9, Huawei Mate 9, Nokia 1, LGE K3 2017
• Android OS version: 8.0, 4.3, 7.0, 8.1 (Go edition), 6.0
• Application version: 257 (CI build numer #20200206.1)

Additional context

Stack trace:

FATAL EXCEPTION: main
Process: com.xfox111.gut.schedule, PID: 28306
android.runtime.JavaProxyThrowable: System.NotSupportedException: Encoding 1251 data could not be found. Make sure you have correct international codeset assembly installed and enabled.
  at System.Text.Encoding.GetEncoding (System.Int32 codepage) [0x0022d] in <a6d893eee8704b7785d1d1b5410d0f5b>:0 
  at System.Text.Encoding.GetEncoding (System.String name) [0x00012] in <a6d893eee8704b7785d1d1b5410d0f5b>:0 
  at GUT.Schedule.Extensions.GetString (System.Net.Http.HttpResponseMessage response) [0x00027] in <2215810725ad4aaeb95d73ce3822a14c>:0 
  at GUT.Schedule.Activities.MainActivity.Export_Click (System.Object sender, System.EventArgs e) [0x002bc] in <2215810725ad4aaeb95d73ce3822a14c>:0 
  at System.Runtime.CompilerServices.AsyncMethodBuilderCore+<>c.<ThrowAsync>b__7_0 (System.Object state) [0x00000] in <a6d893eee8704b7785d1d1b5410d0f5b>:0 
  at Android.App.SyncContext+<>c__DisplayClass2_0.<Post>b__0 () [0x00000] in <03400fe528f64570b9442c743326f3eb>:0 
  at Java.Lang.Thread+RunnableImplementor.Run () [0x00008] in <03400fe528f64570b9442c743326f3eb>:0 
  at Java.Lang.IRunnableInvoker.n_Run (System.IntPtr jnienv, System.IntPtr native__this) [0x00009] in <03400fe528f64570b9442c743326f3eb>:0 
  at (wrapper dynamic-method) Android.Runtime.DynamicMethodNameCounter.7(intptr,intptr)
	at mono.java.lang.RunnableImplementor.n_run(Native Method)
	at mono.java.lang.RunnableImplementor.run(RunnableImplementor.java:30)
	at android.os.Handler.handleCallback(Handler.java:789)
	at android.os.Handler.dispatchMessage(Handler.java:98)
	at android.os.Looper.loop(Looper.java:164)
	at android.app.ActivityThread.main(ActivityThread.java:6938)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:327)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1374)

[XFox111]

Waiting for testers confirmation