What makes a will invalid?

1. The creation of a new will.

2. Marriage (as to the spouse).

3. Incompetence of the testator as designated by a Physician.

4. Undue influence.

5. Fraud.

6. A will that does not meet the technical requirements for a valid will.

7. Discrepancies.

There are other, more complex ways to make a will invalid, however, these are the most basic ones.