ExecuteReader requires an open and available connection SSRS ERROR Report builder 3.0

Question

Using SSRS Report builder 3.0.

Using open query with sql ExecuteReader. Been using this program for months and now have this error when I run a query for a data set

requires an open and available connection. The connection's current state is closed.

How do I open / reset the connection?..

I have tried deleting and resetting the data connection with no Jo

Please help

Answer 1

Copy your query and delete the dataset and recreate it. See that makes any difference.

sometimes for some reason it does that and also check you datasource connection.

also, if this does not work. Try to write simple query for testing purposes. For Instance select * from ...