npgsql: encoding problem for exception text

Win x64 System encoding windows-1251 (Russian) Postgresql installed with default encoding.(9.5.3) If connection.open raise exception, this exception has bad text.(wrong symbols) Sorry for english.

{Npgsql.PostgresException: 28P01: ������������ “user” �� ������ �������� ����������� (�� ������) at Npgsql.NpgsqlConnector.DoReadMessage(DataRowLoadingMode dataRowLoadingMode, Boolean isPrependedMessage) at Npgsql.NpgsqlConnector.ReadMessageWithPrepended(DataRowLoadingMode dataRowLoadingMode) at Npgsql.NpgsqlConnector.HandleAuthentication(String username, NpgsqlTimeout timeout) at Npgsql.NpgsqlConnector.Open(NpgsqlTimeout timeout) at Npgsql.ConnectorPool.Allocate(NpgsqlConnection conn, NpgsqlTimeout timeout) at Npgsql.NpgsqlConnection.OpenInternal() at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.Open() at postgre.test.Program.Main(String[] args) in C:\Users\user\Documents\Visual Studio 2015\Projects\speech\postgre.test\Program.cs:line 71}

System .Text.Encoding .ASCII. GetBytes ( ex.Message )

[1]: 56
[2]: 80
[3]: 48
[4]: 49
[5]: 58
[6]: 32
[7]: 63
[8]: 63
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[10]: 63
[11]: 63
[12]: 63
[13]: 63
[14]: 63
[15]: 63
[16]: 63
[17]: 63
[18]: 63
[19]: 32
[20]: 34
[21]: 117
[22]: 115
[23]: 101
[24]: 114
[25]: 34
[26]: 32
[27]: 63
[28]: 63
[29]: 32
[30]: 63
[31]: 63
[32]: 63
[33]: 63
[34]: 63
[35]: 63
[36]: 32
[37]: 63
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[40]: 63
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[44]: 63
[45]: 32
[46]: 63
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[52]: 63
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[54]: 63
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[57]: 32
[58]: 40
[59]: 63
[60]: 63
[61]: 32
[62]: 63
[63]: 63
[64]: 63
[65]: 63
[66]: 63
[67]: 63
[68]: 41