All homestead entries which have been canceled or relinquished, or are invalid solely because of the erroneous allowance of such entries after the withdrawal of lands for national-forest purposes, may be reinstated or allowed to remain intact, but in the case of entries canceled prior to , applications for reinstatement must have been filed in the proper local land office prior to .March 3, 19111911-03-03July 1, 19121912-07-01