I am not an employer but if I was I would not care about when you had graduated. I only care that you have graduated. what difference does it make if you have a law degree from Harvard and you simply put the wrong graduation date. It is a problem if you state you have a law degree from harvard and when I check I find out you have a gender studies degree.

It happens. Ballpark figure it. It can be difficult to remember every single little detail from 10 years ago exactly.

Although, it can also depend on where you're applying so you should be aware of the company culture before you apply. Some companies would be lax and wouldn't care. Other more popular and competitive companies that receive thousands of applications and have very high professional standards would use that as an excuse to exclude you from the process right away.

Some businesses are very detail-oriented. They could view your mistake as a lack of attention to details and maybe they're looking for a candidate who pays attention to the details since your success on the job and within the company would depend on it.

What do you expect us to do about it?

If they ask about it, tell them you made a mistake. If that's the only error, probably not a big deal.