I am getting a message stating "Return has a W-2 SSN that does not match the taxpayer's or spouse's SSN on the return. I am not married. How do I fix?

Double check that you have entered your Social Security number correctly and double-check that your W-2 shows the correct SSN as well.  

The message is trying to let you know that the W-2 that has been entered is showing a Social Security number that does not match any numbers that have been entered into the tax return.  So, since you are not married and did not enter information for a spouse, the problem is with your SSN.  

If the number is incorrect on your W-2, you should notify your employer and request a corrected W-2.  Otherwise, you will not get proper credit for your wages with the Social Security Administration.

just start e-filing your federal return, in the steps followed it will show a warning to check the W2 SSN. Mine is showing as ***-**-dddd with only the last 4 digit showing. This is the issue. I filled out with my SSN (replace ***_** with real number and it'll fix this error. I was able to file both federal and state after this.