If the only income being reported on the tax return is Social Security benefits then there is no taxable income on the tax return. The IRS will not allow a tax return with no taxable income being reported to be e-filed. It will have to be printed and mailed. Additionally, if the Social Security benefits are your only income then there is no need to file at tax return.
If you still want to file the tax return electronically, although you do not need to file, add $1 of interest income to the tax return. On the Form 1099-INT use any name for the payer and enter $1 in box 1.
Enter 1099-int in the Search box located in the upper right of the program screen. Click on Jump to 1099-int
