Unity fails to read excel using FlexReader plug-in on PC

Unity test version 2018.4.16, released pc package, the following error is reported

NotSupportedException: Encoding 936 data could not be found. Make sure you have correct international codeset assembly installed and enabled.
  at System.Text.Encoding.GetEncoding (System.Int32 codepage) [0x0023f] in <2fa7a6a452ca43df998f07fd1486c0df>:0 
  at ICSharpCode.SharpZipLib.Zip.ZipConstants.ConvertToString (System.Byte[] data, System.Int32 count) [0x00011] in <037da55cb16646df987bb6f3b17470d8>:0 
  at ICSharpCode.SharpZipLib.Zip.ZipConstants.ConvertToStringExt (System.Int32 flags, System.Byte[] data, System.Int32 count) [0x00026] in <037da55cb16646df987bb6f3b17470d8>:0 
  at ICSharpCode.SharpZipLib.Zip.ZipFile.ReadEntries () [0x002e7] in <037da55cb16646df987bb6f3b17470d8>:0 
  at ICSharpCode.SharpZipLib.Zip.ZipFile..ctor (System.IO.Stream stream) [0x00082] in <037da55cb16646df987bb6f3b17470d8>:0 
  at FlexFramework.Excel.WorkBook..ctor (System.Byte[] buffer) [0x0000c] in <d307cfb9d8ab42f6b05ee6a376bd5947>:0 
  at dhg_MMExampleManager+<IELoadExcel>d__20.MoveNext () [0x000b3] in <d307cfb9d8ab42f6b05ee6a376bd5947>:0 
  at UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator enumerator, System.IntPtr returnValueAddress) [0x00027] in <2cc17dca390941eeb4d7b2ff1f84696a>:0 

I used 3.5 before, now just replace it all with 4.0.

Hope it helps you