There is already an open DataReader associated with this Connection which must be closed first.

[Роман Берлов]

MySql.Data.dll 8.0.26 on mono, Ubuntu.
I use pool. When I close connection and after several milliseconds open connection anew that sometimes I get Exception:

"There is already an open DataReader associated with this Connection which must be closed first".

But I don't use DataReader. I use MySqlDataAdapter and call Dispose instance of it every time after executed sql. Also after executed sql I call Dispose for Command instance.

I don't understand where was created DataReader instance.
And note that this problem is missing in MySql.Data.dll 6.10.9 version