I assume that the state tax-exempt dividends are in box 12 of a 1099-DIV. Try the following and see if it eliminates the error.
In the federal income section, after you enter the 1099-DIV, you come to a screen that asks which state the exempt-interest dividends are from. In the drop-down list for the state, all the way at the bottom of the list, select "More Than One State." Do not check the box that says "I earned tax exempt dividends in more than one state." Click Done. The exempt dividends will then be included as taxable income on your state tax return.
