This error prevented me from using TurboTax to file my Minnesota state taxes:
M1 line 5, if present, then dependent must be present and must match dependents on 1040. Xpath: M1 line 5: ReturnState/ReturnDataState/FormM1/ExemptionsAmt
What I believe happened was when I added my two children as dependents I entered their middle initials. TurboTax automatically imported "FirstName X" (X represents middle initial) onto the federal in the first name field. But only imported "FirstName" without the middle initial into the first name field on the state. Since I had already successfully filed my federal there was no way to delete from federal, and there was no way to manually add the initials to the state.
I did call customer service, and spoke with a very helpful representative, and she did invite me to call back and talk with a tax expert if I got rejected again. However, after getting rejected a second time for TurboTax efile and doing my own research, I realized it was easiest to print off the whole state return and mail it to Minnesota directly. It was accepted with no issue.