Commented by: @cincuranet

Provide a test case. Using straightforward code:
conn.Open();
using (var cmd = conn.CreateCommand())
{
cmd.CommandText = "SELECT \"LANGUAGE_REQ\" FROM \"JOB\" WHERE \"MAX_SALARY\"=46900";
using (var reader = cmd.ExecuteReader())
{
while (reader.Read())
{
}
}
}
does not result in any error.

Commented by: fish (fishcodelib)

while (reader.Read()) {
Debug.WriteLine(reader.Item(0)); // Here is the exception thrown
}

Commented by: @cincuranet

There's no `Item` method on `FbDataReader`. I suppose you meant first column from reader. But even the `reader[0]` does not fail. Even the first item from the array does not fail (`((string[])reader[0])[0]`).

Commented by: fish (fishcodelib)

while (reader.Read())
{
System.Diagnostics.Debug.WriteLine((string)reader[0]);// Here is the exception thrown
}
If you set the connection string that includes "Character Set=UTF8;"

Commented by: @cincuranet

OK, so the interesting part is the charset, not the code (which will in this case result in invalid casting). Why it was not included in first place? And stack trace?

Commented by: fish (fishcodelib)

at System.IO.MemoryStream..ctor(Byte[] buffer, Boolean writable)
at System.IO.MemoryStream..ctor(Byte[] buffer)
at FirebirdSql.Data.Client.Managed.XdrStream..ctor(Byte[] buffer, Charset charset)
at FirebirdSql.Data.Client.Managed.Version10.GdsArray.DecodeSlice(Byte[] slice)
at FirebirdSql.Data.Common.ArrayBase.Read()
at FirebirdSql.Data.Common.DbValue.GetArrayData(Int64 handle)
at FirebirdSql.Data.Common.DbValue.GetArray()
at FirebirdSql.Data.Common.DbValue.GetValue()
at FirebirdSql.Data.FirebirdClient.FbDataReader.<>c__DisplayClass43_0.<GetValue>b__0()
at FirebirdSql.Data.FirebirdClient.FbDataReader.CheckedGetValue[T](Func`1 f)
at FirebirdSql.Data.FirebirdClient.FbDataReader.GetValue(Int32 i)
at FirebirdSql.Data.FirebirdClient.FbDataReader.get_Item(Int32 i)

Commented by: @cincuranet

cincuranet/FirebirdSql.Data.FirebirdClient@aabc078