W-2 Box 1 for wages is empty. I enter zero, but I get an error message.

If you have a W-2 without any wages in Box 1, you do not need to enter the W-2 since it cannot be e-filed to the IRS and is not included anywhere on the tax return. The exception is if you have nontaxable combat wages which are shown in Box 12 of the W-2 with a code of "Q" or nontaxable sick pay with a code of "J". If you have combat wages or nontaxable sick pay, enter the W-2 and enter the combat wages or sick pay in Box 12 even if you do not have any wages in Box 1.