There are three Part II sections in the 1040/1040SR Worksheet, one within each of the three schedules, Schedules 1, 2, and 3. I assume you are talking about line 11 in the Deferral for Certain Schedule H or SE Filers Smart Worksheet near the bottom of the 1040/1040SR Worksheet, in Part II of Schedule 3.
I also assume, based on a question you posted a couple of months ago, that you are using the CD/Download TurboTax Premier software in Windows.
First make sure your software is up-to-date. On the Online menu select Check for Updates.
Open the 1040/1040SR Worksheet in forms mode. Are there any other errors in the 1040/1040SR Worksheet? If so, correct the other errors and see if you still have the problem.
Make sure there are no overrides anywhere in your tax return. If an entry has been overridden, the value will be displayed in red instead of black. Remove all overrides and see if you still have the problem.
If the problem still exists, what is on line 10 of the Smart Worksheet? If line 10 is zero or negative you cannot defer any of the tax. But leaving line 11 completely empty should not cause the error. Do you have Supporting Details for line 11? Click on the big plus sign to the left of the entry and make sure that there is nothing entered in the Supporting Details window. If there are no Supporting Details, and you still get the error when there is nothing at all on line 11, I suspect that you may somehow have gotten something in there that does not show up on the screen, but is still there. Click on the space for the line 11 entry and press Backspace and Delete repeatedly until you are sure there is nothing left. The shading should change to blue (or tan if you move away from it).
If that doesn't work, before you try this last solution, save your tax return the way it is, just in case anything goes wrong. With the 1040/1040SR Worksheet open in forms mode, click Delete Form at the bottom. Click Yes to confirm the deletion. The 1040/1040SR Worksheet will be deleted and will immediately be recreated. Line 11 should now be empty, and the error should be gone.
