Cure Notice (FAR 49.402-3 Procedure for Default)
A cure notice must be sent, when the contractor fails to perform some of the other provisions of the contract, other than failing to make make delivery of supplies, or other performance within the specified time. If the termination is predicated upon this type of failure, the contracting officer shall give the contractor written notice, specifying the failure and providing a period of 10 days ( or longer period as necessary) in which to cure the failure.
If a cure notice is not provided, since it is required, the contractor can use the failure to provide a cure notice as a defense for the termination of the contract.
If the contractor does not provide a cure in the required length of time provided by the cure notice, a contracting officer would then provide a "Show Cause Letter (FAR 49.607)" as the final warning that default is imminent unless the contractor is able to demonstrate why the contract should not be terminated.