Some evaluations may issue error messages:

To suppress the error messages, wrap the input expression with Quiet:

To suppress a particular error message for the remainder of the session, click the "More information" icon to the left of the message, choose Turn Off This Message, and click OK:

Subsequent evaluations will not produce the message:

It is sometimes useful to turn off an error message programmatically. To do so, you need the message’s name.

If an evaluation has issued a message, you can see its name by clicking the "More information" icon on its left:

Use Off to turn that message off for the remainder of the session:

Subsequent evaluations will not produce that message:

Turn the message back on again with On:

The message is restored: